Moved DBremWatcher to plugins directory

[revering]

Backport of #38994

This avoids having the module be registered in multiple shared libraries.
Code compiles, and cmsRun finds the plugin in the new location.

[cmsbuild]

A new Pull Request was created by @revering for CMSSW_10_6_X.

It involves the following packages:

• SimG4Core/CustomPhysics (simulation)

@cmsbuild, @civanch, @mdhildreth can you please review it and eventually sign? Thanks.
@makortel, @bsunanda, @rovere, @fabiocos, @slomeo this is something you requested to watch as well.
@perrotta, @dpiparo, @qliphy, @rappoccio you are the release manager for this.

cms-bot commands are listed here

• Backported from Moved DBremWatcher to plugins directory #38994

[civanch]

please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-18ce2f/26717/summary.html
COMMIT: b3f5df3
CMSSW: CMSSW_10_6_X_2022-08-07-0000/slc7_amd64_gcc700
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/39004/26717/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 2 differences found in the comparisons
• DQMHistoTests: Total files compared: 35
• DQMHistoTests: Total histograms compared: 3215686
• DQMHistoTests: Total failures: 2
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3215350
• DQMHistoTests: Total skipped: 334
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 34 files compared)
• Checked 143 log files, 29 edm output root files, 35 DQM output files
• TriggerResults: no differences found

[civanch]

+1

pure technical change

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_10_6_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_12_5_X is complete. This pull request will now be reviewed by the release team before it's merged. @perrotta, @dpiparo, @qliphy, @rappoccio (and backports should be raised in the release meeting by the corresponding L2)

[qliphy]

+1