We can keep only unit tests in plugins instead of starting each time a local node and running tests against it.
Also follow up of #12091
Tests can use more than one JVM
We don't need anymore to set the number of jvm to run tests as we moved IT to Rest Tests
For all plugins but cloud plugins which will require another way for running integration tests.
Follow up for https://github.com/elastic/elasticsearch-analysis-kuromoji/issues/61
We don't shade anymore elasticsearch dependencies, so plugins might include jars in the distribution ZIP file which might not be needed anymore.
For example, `elasticsearch-cloud-aws` comes with:
```
Archive: cloud-aws/target/releases/elasticsearch-cloud-aws-2.0.0-SNAPSHOT.zip
Length Date Time Name
-------- ---- ---- ----
1920788 05-18-15 09:42 aws-java-sdk-ec2-1.9.34.jar
503963 05-18-15 09:42 aws-java-sdk-core-1.9.34.jar
232771 01-19-15 09:24 commons-codec-1.6.jar
915096 01-19-15 09:24 jackson-databind-2.3.2.jar
252288 05-18-15 09:42 aws-java-sdk-kms-1.9.34.jar
62050 01-19-15 09:24 commons-logging-1.1.3.jar
282269 10-31-14 13:19 httpcore-4.3.2.jar
35058 01-19-15 09:24 jackson-annotations-2.3.0.jar
229998 05-29-15 12:28 jackson-core-2.5.3.jar
589289 01-19-15 09:24 joda-time-2.7.jar
562858 05-18-15 09:42 aws-java-sdk-s3-1.9.34.jar
590533 10-31-14 13:19 httpclient-4.3.5.jar
44854 06-12-15 19:22 elasticsearch-cloud-aws-2.0.0-SNAPSHOT.jar
-------- -------
6221815 13 files
```
A lot of those files are already distributed with elasticsearch itself so classes are available within the classloader.
We mark all es core dependencies as provided in plugins.
We also remove `groupId` as already defined in parent pom.
And we remove non needed licenses files as some jars are not included anymore in plugins.
Closes#11647.