[DQM] Fix for DQM merging exception due to duplicated labels 12_2_X

[jfernan2]

PR description:

Backport of #36778

This PR fixes the crash in DQM merging due to duplicated lables reported on:
https://hypernews.cern.ch/HyperNews/CMS/get/tier0-Ops/2328/1/1/1/1/1.html

[jfernan2]

please test

[cmsbuild]

A new Pull Request was created by @jfernan2 for CMSSW_12_2_X.

It involves the following packages:

• DQM/DTMonitorModule (dqm)

@emanueleusai, @ahmad3213, @jfernan2, @rvenditti, @pbo0, @pmandrik can you please review it and eventually sign? Thanks.
@battibass this is something you requested to watch as well.
@perrotta, @dpiparo, @qliphy you are the release manager for this.

cms-bot commands are listed here

• Backported from [DQM] Fix for DQM merging exception due to duplicated labels #36778

[perrotta]

backport of #36778

[tvami]

Type bug-fix

[cmsbuild]

-1

Failed Tests: RelVals-INPUT
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-2ccbb9/21919/summary.html
COMMIT: dcc7f51
CMSSW: CMSSW_12_2_X_2022-01-21-2300/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/36779/21919/install.sh to create a dev area with all the needed externals and cmssw changes.

RelVals-INPUT

• 4.764.76_ZMuSkim2012D+ZMuSkim2012D+HLTDSKIM2+RECODR1reHLT2+HARVESTDR1reHLT/step2_ZMuSkim2012D+ZMuSkim2012D+HLTDSKIM2+RECODR1reHLT2+HARVESTDR1reHLT.log

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 13 differences found in the comparisons
• DQMHistoTests: Total files compared: 42
• DQMHistoTests: Total histograms compared: 3250594
• DQMHistoTests: Total failures: 183
• DQMHistoTests: Total nulls: 1
• DQMHistoTests: Total successes: 3250388
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: -0.004 KiB( 41 files compared)
• DQMHistoSizes: changed ( 312.0 ): -0.004 KiB MessageLogger/Warnings
• Checked 177 log files, 37 edm output root files, 42 DQM output files
• TriggerResults: no differences found

[jfernan2]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_12_2_X IBs (but tests are reportedly failing) and once validation in the development release cycle CMSSW_12_3_X is complete. This pull request will now be reviewed by the release team before it's merged. @perrotta, @dpiparo, @qliphy (and backports should be raised in the release meeting by the corresponding L2)

[perrotta]

+1

[perrotta]

merge