[GEM] Introducing GE21 rechit container for Run 3

[yeckang]

PR description:

This PR enables saving the GEMRecHits from GE21 chambers, which are installed for testing purposes.
Currently, we are not saving them because of the possibility of interruption in the muon reconstruction performance.
However, several groups studying GE21 performance continue to ask if we can save them.
For this reason, GEM DPG decides to save them in a separate rechit container, which does not propagate to the muon reco system.

PR validation:

The PR is tested on the Run 3 and Run 4 conditions with the TenMu scenario.
We also checked that there is no effect on the muon reconstruction performance.
You can check the details from the DPG slide.

[cmsbuild]

cms-bot internal usage

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-49476/46954

[cmsbuild]

A new Pull Request was created by @yeckang for master.

It involves the following packages:

• RecoLocalMuon/GEMRecHit (reconstruction)

@cmsbuild, @jfernan2, @mandrenguyen, @srimanob can you please review it and eventually sign? Thanks.
@bellan, @jhgoh, @jshlee, @watson-ij this is something you requested to watch as well.
@ftenchini, @mandrenguyen, @sextonkennedy you are the release manager for this.

cms-bot commands are listed here

[watson-ij]

please test

[cmsbuild]

+1

Size: This PR adds an extra 20KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-660d59/49691/summary.html
COMMIT: 34ba286
CMSSW: CMSSW_16_0_X_2025-11-25-2300/el8_amd64_gcc13
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/49476/49691/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 3 lines to the logs
• ROOTFileChecks: Some differences in event products or their sizes found
• Reco comparison results: 5 differences found in the comparisons
• Reco comparison had 4 failed jobs
• DQMHistoTests: Total files compared: 53
• DQMHistoTests: Total histograms compared: 4269233
• DQMHistoTests: Total failures: 15
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 4269198
• DQMHistoTests: Total skipped: 20
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 52 files compared)
• Checked 227 log files, 198 edm output root files, 53 DQM output files
• TriggerResults: no differences found

[cmsbuild]

Milestone for this pull request has been moved to CMSSW_16_1_X. Please open a backport if it should also go in to CMSSW_16_0_X.