HADOOP-17454. [s3a] Disable bucket existence check - set fs.s3a.bucket.probe to 0 (#2593)

Also fixes HADOOP-16995. ITestS3AConfiguration proxy tests failures when bucket probes == 0
The improvement should include the fix, because the test would fail by default otherwise.

Change-Id: I9a7e4b5e6d4391ebba096c15e84461c038a2ec59

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/Constants.java

@@ -518,7 +518,7 @@ public final class Constants {
    * will be validated using {@code S3AFileSystem.verifyBucketExistsV2()}.
    * Value: {@value}
    */
-  public static final int S3A_BUCKET_PROBE_DEFAULT = 2;
+  public static final int S3A_BUCKET_PROBE_DEFAULT = 0;
 
   /**
    * How long a directory listing in the MS is considered as authoritative.

hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/index.md

@@ -1040,9 +1040,9 @@ options are covered in [Testing](./testing.md).
 
 <property>
   <name>fs.s3a.bucket.probe</name>
-  <value>2</value>
+  <value>0</value>
   <description>
-     The value can be 0, 1 or 2 (default).
+     The value can be 0 (default), 1 or 2.
      When set to 0, bucket existence checks won't be done
      during initialization thus making it faster.
      Though it should be noted that when the bucket is not available in S3,

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/ITestS3AConfiguration.java

@@ -159,6 +159,7 @@ public class ITestS3AConfiguration {
     return intercept(clazz,
         () -> {
           fs = S3ATestUtils.createTestFileSystem(conf);
+          fs.listFiles(new Path("/"), false);
           return "expected failure creating FS " + text + " got " + fs;
         });
   }