[XRootD] Update xrootd version to 5.9.4

[akritkbehera]

This contains many bug fixes see https://github.com/xrootd/xrootd/releases/tag/v5.9.4 for details

[akritkbehera]

please test

[cmsbuild]

A new Pull Request was created by @akritkbehera for branch IB/CMSSW_17_0_X/master.

@akritkbehera, @iarspider, @raoatifshad, @smuzaffar can you please review it and eventually sign? Thanks.
@ftenchini, @mandrenguyen, @sextonkennedy you are the release manager for this.
cms-bot commands are listed here

[cmsbuild]

cms-bot internal usage

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-b51e3a/53293/summary.html
COMMIT: cce1217
CMSSW: CMSSW_17_0_X_2026-05-18-1100/el8_amd64_gcc13
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmsdist/10561/53293/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 12 lines to the logs
• Reco comparison results: 5 differences found in the comparisons
• DQMHistoTests: Total files compared: 53
• DQMHistoTests: Total histograms compared: 4187292
• DQMHistoTests: Total failures: 36
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 4187236
• DQMHistoTests: Total skipped: 20
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 52 files compared)
• Checked 227 log files, 197 edm output root files, 53 DQM output files
• TriggerResults: no differences found

[smuzaffar]

+externals

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next IB/CMSSW_17_0_X/master IBs (tests are also fine). This pull request will now be reviewed by the release team before it's merged. @ftenchini, @sextonkennedy, @mandrenguyen (and backports should be raised in the release meeting by the corresponding L2)