Improve discover method in cond2xml for read-only and patch releases

[francescobrivio]

PR description:

Starting from the discussion in #42292 and following Marino's suggestion in missirol@ea229a8, this PR fixes the way in which conddb retrieves the pluginUtilities_payload2xml.so library to dump payload content, especially for patch releases.

Note: The issue was already nicely solved in #42324, this PR simply rewrites some code to make it more clear (at least more clear to me). Additionally, it fixes the Exception printout message in case "No XML converter is found..."

PR validation:

Code compiles plus a few local tests using the discover function that is updated here.

Backport:

Not a backport, but to be backported all the way back to 13_0_X.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-42357/36389

• This PR adds an extra 16KB to repository

[cmsbuild]

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

It involves the following packages:

• CondCore/Utilities (db)

@perrotta, @consuegs, @cmsbuild, @saumyaphor4252, @francescobrivio, @tvami can you please review it and eventually sign? Thanks.
@mmusich this is something you requested to watch as well.
@perrotta, @dpiparo, @rappoccio you are the release manager for this.

cms-bot commands are listed here

[tvami]

@cmsbuild , please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-494ce4/33876/summary.html
COMMIT: 770fcf3
CMSSW: CMSSW_13_3_X_2023-07-25-1100/el8_amd64_gcc11
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/42357/33876/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 10 lines to the logs
• Reco comparison results: 5 differences found in the comparisons
• DQMHistoTests: Total files compared: 48
• DQMHistoTests: Total histograms compared: 3150117
• DQMHistoTests: Total failures: 3
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3150092
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 47 files compared)
• Checked 207 log files, 159 edm output root files, 48 DQM output files
• TriggerResults: no differences found

[tvami]

+1

[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, @rappoccio (and backports should be raised in the release meeting by the corresponding L2)

[perrotta]

+1