Keep HI Gen collections when pp reco is customized for XeXe (94X back…

[mandrenguyen]

For certain MC productions it's necessary to keep information about the geometry of colliding nuclei for centrality determination.
The heavy ion eras keep these collections, as the heavy ion event content stores them:
SimGeneral/Configuration/python/SimGeneral_HiMixing_EventContent_cff.py
However, for XeXe we use the standard pp event content.
This PR expands that event content for the XeXe era.
The extra collection is stored in the DIGI and RECO steps:
edm::GenHIEvent "heavyIon" "" "HLT"

This is a backport of #21760

@gsfs

[cmsbuild]

A new Pull Request was created by @mandrenguyen (Matthew Nguyen) for CMSSW_9_4_X.

It involves the following packages:

SimGeneral/Configuration

@cmsbuild, @civanch, @mdhildreth can you please review it and eventually sign? Thanks.
@davidlange6, @slava77, @fabiocos you are the release manager for this.

cms-bot commands are listed here

[civanch]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/25309/console Started: 2018/01/03 23:26

[cmsbuild]

+1
Tested at: 569b506
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-21761/25309/summary.html

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-21761/25309/summary.html

@slava77 comparisons for the following workflows were not done due to missing matrix map:

• /build/cmsbld/jenkins-workarea/workspace/compare-root-files-short-matrix/results/JR-comparison/PR-21761/1325.7_TTbar_13_94XNanoAODINPUT+TTbar_13_94XNanoAODINPUT+NANOEDMMC2017

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 25
• DQMHistoTests: Total histograms compared: 2717599
• DQMHistoTests: Total failures: 111
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2717326
• DQMHistoTests: Total skipped: 162
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0 KiB( 0 files compared)
• Checked 106 log files, 9 edm output root files, 25 DQM output files

[civanch]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_9_4_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_10_0_X is complete. This pull request will now be reviewed by the release team before it's merged. @davidlange6, @slava77, @smuzaffar, @fabiocos (and backports should be raised in the release meeting by the corresponding L2)

[fabiocos]

+1