[release] Prepare release coreunstable-beta.2

[opentelemetrybot]

Note: This PR was opened automatically by the prepare release workflow.

Requested by: @CodeBlanch

Changes

• CHANGELOG files updated for projects being released.
• Public API files updated for projects being released (only performed for stable releases).

  Commands

/UpdateReleaseDates: Use to update release dates in CHANGELOGs before merging [approvers, maintainers] /CreateReleaseTag: Use after merging to push the release tag and trigger the job to create packages [approvers, maintainers] /PushPackages: Use after the created packages have been validated to push to NuGet [maintainers]

[CodeBlanch]

Hmm this shouldn't have updated public api files.