[FEATURE] Add a CI workflow to test CCR integ test suite with remote store enabled indices.

[ankitkala]

We can't write specific ITs to test this as remote store is enabled for all indices at cluster level. To get around this, we can expose an optional flag to set remote store specific settings on leader cluster in build.gradle and run the integ test in github CI. This should be helpful in ensuring that we're able to catch any regression in this code path.