technical fix for PixelJetPuId

[missirol]

PR description:

This PR fixes an UBSAN-IB error from the HLT module PixelJetPuId, as reported in #35008.

This update is merely technical [*]. No changes in outputs are expected.

[*] Now, if tracks.size()==0, the two arrays are created with size=1 (not 0), but are still not used.

PR validation:

Verified that the update solves the original error, using a recent UBSAN IB.

If this PR is a backport, please specify the original PR and why you need to backport that PR:

N/A

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-36060/26524

• This PR adds an extra 16KB to repository

[cmsbuild]

A new Pull Request was created by @missirol (Marino Missiroli) for master.

It involves the following packages:

• HLTrigger/JetMET (hlt)

@cmsbuild, @missirol, @Martin-Grunewald can you please review it and eventually sign? Thanks.
@Martin-Grunewald, @silviodonato 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

[missirol]

please test with #36021

the other PR is needed only to fix unrelated problems with some of the PR tests

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-97151a/20402/summary.html
COMMIT: 73a87c2
CMSSW: CMSSW_12_2_X_2021-11-09-1100/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/36060/20402/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: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 42
• DQMHistoTests: Total histograms compared: 2901890
• DQMHistoTests: Total failures: 0
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2901868
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 41 files compared)
• Checked 177 log files, 37 edm output root files, 42 DQM output files
• TriggerResults: no differences found

[missirol]

+hlt

• technical update to fix an error in UBSAN IBs
• the label requires-external should be ignored (another PR was required for testing due to unrelated reasons)

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs (tests are also fine). 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)

[qliphy]

+1