[release] Prepare release core-1.15.0

[otelbot-dotnet]

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

Requested by: @rajkumar-rangaraj

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]
/UpdateReleaseNotes: Use to update RELEASENOTES.md 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]

[otelbot-dotnet]

I noticed this PR is releasing a stable version of core packages but there isn't any content in RELEASENOTES.md for the version being released.

It is important to update RELEASENOTES.md before creating the release tag because a permalink will become part of the package(s).

Post a comment with "/UpdateReleaseNotes" in the body if you would like me to update release notes.

Note: In the comment everything below "/UpdateReleaseNotes" will be added to RELEASENOTES.md for the version being released. If something is already there it will be replaced.

[Kielek]

/UpdateReleaseNotes

• Added support for ActivitySource.TelemetrySchemaUrl
  and Meter.TelemetrySchemaUrl properties across exporters.
• Improved performance and reduced memory consumption for metrics histograms.
• Added mTLS configuration support for the OTLP exporter (client cert/key and
  CA certificate options).
• OpenTelemetry.Exporter.Zipkin is deprecated and will stop receiving updates
  in December 2026. Zipkin already supports OTLP ingestion.
  Migrate to OpenTelemetry.Exporter.OpenTelemetryProtocol as stated
  in the Deprecating Zipkin Exporter blog post.

[otelbot-dotnet]

I updated RELEASENOTES.md.

[Kielek]

/UpdateReleaseDates

[otelbot-dotnet]

I updated the CHANGELOG release dates.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.93%. Comparing base (5f3a8ef) to head (1cc7c7d).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6839   +/-   ##
=======================================
  Coverage   86.92%   86.93%           
=======================================
  Files         263      263           
  Lines       12382    12382           
=======================================
+ Hits        10763    10764    +1     
+ Misses       1619     1618    -1     

Flag	Coverage Δ
unittests-Project-Experimental	86.71% <ø> (-0.13%)	⬇️
unittests-Project-Stable	86.77% <ø> (-0.07%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.
see 2 files with indirect coverage changes

[otelbot-dotnet]

I noticed this PR was merged.

Post a comment with "/CreateReleaseTag" in the body if you would like me to create the release tag core-1.15.0 for the merge commit which will trigger the package workflow.

[Kielek]

/CreateReleaseTag

[otelbot-dotnet]

I just pushed the core-1.15.0 tag.

The package workflow should begin momentarily.

[Kielek]

/PushPackages