Improve the time taken by Github Actions on pull requests

[VachaShah]

Coming from opensearch-project/opensearch-clients#53, update the workflows to reduce the amount of time taken by Github actions for integration tests.

[shyim]

I took #108 as reference. A integration test takes like 1 minute to complete. Only the slow ones are Unreleased versions where we have to compile Java. I guess it's fine for this PHP SDK

[VachaShah]

@shyim Sorry I meant using the Github cache and improving the logic for docker images to reduce the time for integration tests against unreleased versions. Would we not need to do that for the PHP client?

[dblock]

In #180 integration tests cache the min distribution and are now fast.