feat(single-test): add single test run capability

[elamirKad]

Description

This PR adds the ability to run a single test from the test suite using the -k flag for pytest, making it easier for developers to test specific functionality during development.
Now it is possible to test a single test by running:
./.ci/run-tests true 1.3.0 name_of_the_test

Issues Resolved

Closes #317

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[saimedhi]

Hello @elamirKad, Please try to fix the failing Integration tests. And also add your change to CHANGELOG.md file.

[elamirKad]

Hello @saimedhi, I believe I have fixed integration tests and made the necessary additions to the CHANGELOG.md file.

[saimedhi]

Hello @saimedhi, I believe I have fixed integration tests and made the necessary additions to the CHANGELOG.md file.

Thanks for the changes @elamirKad. I have one more suggestion, could you please merge your 3 commits into one commit.

[dblock]

This is nice. Nitpick: the pytest docs for -k say "Run tests by keyword expressions". Should we call this TEST_KEYWORD?

Let's document this in https://github.com/opensearch-project/opensearch-py/blob/main/DEVELOPER_GUIDE.md

[harshavamsi]

@elamirKad want to finish this?

[saimedhi]

Hello @elamirKad, Thank you for contributing to the opensearch-py repository. Would you like to finish this?

[saimedhi]

@elamirKad, Kindly complete the pull request. This will be very helpful for developers. Thanks.