Migrate skeletons to catch2 v3 (follow-up on #49121)

[iarspider]

PR description:

Follow-up on #49121 to fix failing TestFWCoreSkeletons unit test:

>> Compiling  src/TestSubsystem/TestEDAnalyzer/test/test_catch2_TestEDAnalyzer.cc
src/TestSubsystem/TestEDAnalyzer/test/test_catch2_TestEDAnalyzer.cc:1:10: fatal error: catch.hpp: No such file or directory
    1 | #include "catch.hpp"
      |          ^~~~~~~~~~~
compilation terminated.

PR validation:

Bot tests

[iarspider]

please test

[cmsbuild]

cms-bot internal usage

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-49166/46461

[cmsbuild]

A new Pull Request was created by @iarspider for master.

It involves the following packages:

• FWCore/Skeletons (core)
• FWCore/TestProcessor (core)
• PhysicsTools/TensorFlow (ml)

@Dr15Jones, @hjkwon260, @makortel, @smuzaffar, @valsdav, @y19y19 can you please review it and eventually sign? Thanks.
@makortel, @riga, @wddgit this is something you requested to watch as well.
@ftenchini, @mandrenguyen, @sextonkennedy you are the release manager for this.

cms-bot commands are listed here

[cmsbuild]

+1

Size: This PR adds an extra 28KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-a256f4/48685/summary.html
COMMIT: 2a8652f
CMSSW: CMSSW_16_0_X_2025-10-14-2300/el8_amd64_gcc13
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/49166/48685/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 4 lines to the logs
• Reco comparison results: 6 differences found in the comparisons
• DQMHistoTests: Total files compared: 51
• DQMHistoTests: Total histograms compared: 3940073
• DQMHistoTests: Total failures: 43
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3940010
• DQMHistoTests: Total skipped: 20
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 50 files compared)
• Checked 218 log files, 188 edm output root files, 51 DQM output files
• TriggerResults: no differences found

[makortel]

+core

[hjkwon260]

+ml

[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. @mandrenguyen, @sextonkennedy, @ftenchini (and backports should be raised in the release meeting by the corresponding L2)

[mandrenguyen]

+1