Release version 1.2

[dblock]

Coming from opensearch-build#567, release version 1.2. Please follow the following checklist.

Preparation

• Assign this issue to a release owner.
• Finalize scope and feature set and update the Public Roadmap.
• Create, update, triage and label all features and issues targeted for this release with v1.2.0.

CI/CD

• Increment version on main to 1.2.0.0.
• Ensure working and passing CI.
• Re(add) this repo to the manifest.

Pre-Release

• Branch and build from a 1.2 branch.
• Update your branch in the manifest.
• Feature complete, pencils down.
• Fix bugs that target this release.

Release

• Complete documentation.
• Gather, review and publish release notes.
• Verify all issued labeled for this release are closed or labelled for the next release.

Post Release

• Create a release tag.
• Suggest improvements to this template.
• Conduct a postmortem, and publish its results.

[peternied]

@jackiehanyang @ylwu-amzn Until Friday the 12th at noon PST, any tests that use distribution downloader were running against old bits and need to be rerun. Can you please see if your team was impacted, rerun the tests, and then mark the tests run as completed in opensearch-project/opensearch-build#954?

Note; I believe we talked about this offline in our internal release channel, but I want to be sure that everyone is informed and has completed their testing.