Integration/BWC tests for OpenSearch native plugins

[prudhvigodithi]

Is your feature request related to a problem? Please describe.
The native plugins part of OpenSearch, do not a have a proper Integration/BWC test framework like other plugins do have, other plugins here refer to the plugins part of the GH opensearch-project org. The existing gradle check, I believe does some basic build and complication tests, but not a full blown Integration/BWC tests.
Now work is in progress to migrate the job-scheduler to be part of native plugins, job-scheduler at its own repo has full suite Integration/BWC tests, but its not worth to migrate those test setups to the core, instead having a general Integration/BWC test framework that can cover all the native plugins is good idea.

Describe the solution you'd like
A generic gradle task can be used to call Integration/BWC test framework for native plugins.
This gradle task can be wired to CI setup and can be executed daily just like its done for other plugins in opensearch-project org.

[prudhvigodithi]

Adding @dblock @bbarani @saratvemulapalli @joshpalis @minalsha @peterzhuamazon @gaiksaya @reta

[peterzhuamazon]

Thanks @prudhvigodithi for this issue here.
I am thinking what kind of testing can we do for native plugins.
They are checked in gradle check already, ex: repository-s3.

Job Scheduler as a new comer would love some tests as it does not have integTest to start with.
Need to understand the scope of the tests required here.

Thanks.