[HGCAL trigger] Revert const back to constexpr

[jbsauvan]

Revert to constexpr instead of const, following comment in #28385

[cmsbuild]

The code-checks are being triggered in jenkins.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-28460/12894

• This PR adds an extra 12KB to repository

[cmsbuild]

A new Pull Request was created by @jbsauvan (Jean-Baptiste Sauvan) for master.

It involves the following packages:

L1Trigger/L1THGCal

@cmsbuild, @rekovic, @benkrikler, @kpedro88 can you please review it and eventually sign? Thanks.
@Martin-Grunewald, @amarini, @lgray this is something you requested to watch as well.
@davidlange6, @slava77, @fabiocos you are the release manager for this.

cms-bot commands are listed here

[fabiocos]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-run-pr-tests/3608/console Started: 2019/11/24 18:28

[cmsbuild]

+1
Tested at: 1d2b887
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-f0fb70/3608/summary.html

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-f0fb70/3608/summary.html

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 3 differences found in the comparisons
• DQMHistoTests: Total files compared: 34
• DQMHistoTests: Total histograms compared: 2785613
• DQMHistoTests: Total failures: 2
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2785270
• DQMHistoTests: Total skipped: 341
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 33 files compared)
• Checked 147 log files, 16 edm output root files, 34 DQM output files

[kpedro88]

+upgrade

[fabiocos]

+1

[fabiocos]

merge

@rekovic please check