Update the release process per changes to the org #6912

Is your feature request related to a problem? Please describe.

The GitHub organization is no longer allowing automatic creation of tags. Nor can we use the GitHub application for writing the change log.

We create a tag here:

https://github.com/opensearch-project/data-prepper/blob/main/.github/workflows/release.yml#L184-L194

This also is what creates our Jenkins workflow.

This section is also now invalid.

https://github.com/opensearch-project/data-prepper/blob/main/.github/workflows/release.yml#L230-L235

Describe the solution you'd like

Update the release process to work with these changes to the organization.

Because we can no longer create tags, the release workflow will now only verify that the tag exists and matches the current version in gradle.properties.

Also, both our release and release-prepare-branch GitHub Actions current create PRs. The release creates these for the changelog and the release-prepare-branch creates these to create a PR with the updated version and THIRD-PARTY file update. These GHAs may not longer create PRs using this repo's credentials. Instead it will use a new fork provided by https://github.com/opensearch-ci-bot. The PRs will come from this bot and the Data Prepper repo will have a personal access token (PAT) for this user.

Describe alternatives you've considered (Optional)

N/A

Additional context

N/A