Fix remove of azure files

Probably when we updated Azure SDK, we introduced a regression.
Actually, we are not able to remove files anymore.

For example, if you register a new azure repository, the snapshot service tries to create a temp file and then remove it.
Removing does not work and you can see in logs:

```
[2016-05-18 11:03:24,914][WARN ][org.elasticsearch.cloud.azure.blobstore] [azure] can not remove [tests-ilmRPJ8URU-sh18yj38O6g/] in container {elasticsearch-snapshots}: The specified blob does not exist.
```

This fix deals with that. It now list all the files in a flatten mode, remove in the full URL the server and the container name.

As an example, when you are removing a blob which full name is `https://dpi24329.blob.core.windows.net/elasticsearch-snapshots/bar/test` you need to actually call Azure SDK with `bar/test` as the path, `elasticsearch-snapshots` is the container.

To run the test, you need to pass some parameters: `-Dtests.thirdparty=true -Dtests.config=/path/to/elasticsearch.yml`

Where `elasticsearch.yml` contains something like:

```
cloud.azure.storage.default.account: account
cloud.azure.storage.default.key: key
```

Related to #16472
Closes #18436.

plugins/repository-azure/src/main/java/org/elasticsearch/cloud/azure/storage/AzureStorageServiceImpl.java

@@ -182,13 +182,20 @@ public class AzureStorageServiceImpl extends AbstractLifecycleComponent<AzureSto
         CloudBlobClient client = this.getSelectedClient(account, mode);
         CloudBlobContainer blob_container = client.getContainerReference(container);
         if (blob_container.exists()) {
-            for (ListBlobItem blobItem : blob_container.listBlobs(path)) {
-                logger.trace("removing blob [{}]", blobItem.getUri());
-                deleteBlob(account, mode, container, blobItem.getUri().toString());
+            for (ListBlobItem blobItem : blob_container.listBlobs(path, true)) {
+                String blobName = blobNameFromUri(container, blobItem.getUri());
+                logger.trace("removing blob [{}] full URI was [{}]", blobName, blobItem.getUri());
+                deleteBlob(account, mode, container, blobName);
             }
         }
     }
 
+    public static String blobNameFromUri(String container, URI uri) {
+        String path = uri.getPath();
+        // We remove the container name from the path
+        return path.replaceFirst("/" + container + "/", "");
+    }
+
     @Override
     public boolean blobExists(String account, LocationMode mode, String container, String blob) throws URISyntaxException, StorageException {
         // Container name must be lower case.

plugins/repository-azure/src/test/java/org/elasticsearch/repositories/azure/AzureBlobStoreTests.java

@@ -0,0 +1,76 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.repositories.azure;
+
+import com.microsoft.azure.storage.StorageException;
+import org.elasticsearch.cloud.azure.blobstore.AzureBlobStore;
+import org.elasticsearch.cloud.azure.storage.AzureStorageService;
+import org.elasticsearch.cloud.azure.storage.AzureStorageServiceImpl;
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.blobstore.BlobStore;
+import org.elasticsearch.common.io.PathUtils;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.settings.SettingsException;
+import org.elasticsearch.repositories.RepositoryName;
+import org.elasticsearch.repositories.RepositorySettings;
+import org.elasticsearch.test.ESBlobStoreTestCase;
+import org.elasticsearch.test.ESIntegTestCase;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+
+/**
+ * You must specify {@code -Dtests.thirdparty=true -Dtests.config=/path/to/elasticsearch.yml}
+ * in order to run these tests.
+ */
+@ESIntegTestCase.ThirdParty
+public class AzureBlobStoreTests extends ESBlobStoreTestCase {
+    @Override
+    protected BlobStore newBlobStore() throws IOException {
+        try {
+            RepositoryName repositoryName = new RepositoryName("azure", "ittest");
+            Settings settings = readSettingsFromFile();
+            RepositorySettings repositorySettings = new RepositorySettings(settings, Settings.builder().build());
+            AzureStorageService storageService = new AzureStorageServiceImpl(settings);
+            AzureBlobStore blobStore = new AzureBlobStore(repositoryName, settings, repositorySettings, storageService);
+            blobStore.createContainer(blobStore.container());
+            return blobStore;
+        } catch (URISyntaxException | StorageException e) {
+            throw new IOException(e);
+        }
+    }
+
+    protected Settings readSettingsFromFile() {
+        Settings.Builder settings = Settings.builder();
+
+        // if explicit, just load it and don't load from env
+        try {
+            if (Strings.hasText(System.getProperty("tests.config"))) {
+                settings.loadFromPath(PathUtils.get((System.getProperty("tests.config"))));
+            } else {
+                throw new IllegalStateException("to run integration tests, you need to set -Dtests.thirdparty=true and -Dtests.config=/path/to/elasticsearch.yml");
+            }
+        } catch (SettingsException exception) {
+            throw new IllegalStateException("your test configuration file is incorrect: " + System.getProperty("tests.config"), exception);
+        }
+        return settings.build();
+    }
+
+}