[Backport 2.x] Updates integTest behavior to accept the version and set the password accordingly and removes admin:admin reference from the Handbook

[DarshitChanpura]

Backports https://github.com/opensearch-project/cross-cluster-replication/commit/3ea239b5b308b8c053511fb2da79ac37f12b2340 from https://github.com/opensearch-project/cross-cluster-replication/pull/1298

Backports d703887f88f24c444e0513ebeca21e30b93354f8 from #1318

Check List

• [ ] New functionality includes testing.
  • [x] All tests pass
• [x] New functionality has been documented.
  • [x] New functionality has javadoc added
• [x] Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license. For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (7e2902c) 76.19% compared to head (9212cd2) 76.29%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## 2.x #1327 +/- ## ============================================ + Coverage 76.19% 76.29% +0.10% - Complexity 1047 1051 +4 ============================================ Files 141 141 Lines 4784 4784 Branches 526 526 ============================================ + Hits 3645 3650 +5 + Misses 787 784 -3 + Partials 352 350 -2 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.