[12_3_X] Fix typo in L1T prescales files

[francescobrivio]

PR description:

Backport of #37582
This PR fixes a typo introduced in #37453 by adding back the .xml string in the L1T prescale files.
The typo is a blocker for the correct operations of the L1T O2Os so it should be fixed asap.

PR validation:

Code compiles.
@cms-sw/l1-l2 please comment if further tests are needed on your side.

Backport:

Backport of #37582

FYI @dpiparo @cms-sw/db-l2 @panoskatsoulis @elfontan @boudoul

[francescobrivio]

backport of #37582

[cmsbuild]

A new Pull Request was created by @francescobrivio for CMSSW_12_3_X.

It involves the following packages:

• L1Trigger/L1TGlobal (l1)

@epalencia, @cmsbuild, @cecilecaillol, @rekovic can you please review it and eventually sign? Thanks.
@Martin-Grunewald, @missirol 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 Fix typo in L1T prescales files #37582

[francescobrivio]

urgent

• blocks L1T O2O operations

[tvami]

type bug-fix

[francescobrivio]

@cmsbuild please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-fa56ea/23951/summary.html
COMMIT: 55ed6b7
CMSSW: CMSSW_12_3_X_2022-04-15-1100/slc7_amd64_gcc10
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/37583/23951/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: 4 differences found in the comparisons
• DQMHistoTests: Total files compared: 49
• DQMHistoTests: Total histograms compared: 3697381
• DQMHistoTests: Total failures: 8
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3697351
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 48 files compared)
• Checked 204 log files, 45 edm output root files, 49 DQM output files
• TriggerResults: no differences found

[qliphy]

merge
by pass L1, the master PR has already been signed and tested