AlpakaServiceSerialSync should always be available [15.0.x]

[fwyzard]

PR description:

The AlpakaServiceSerialSync should always be available, even if the "cpu" accelerator is not listed in process.options.accelerators.

PR validation:

The workflows 141.044407 and 141.044483 were failing due to the missing AlpakaServiceSerialSync in step3.
With these changes they run successfully.

If this PR is a backport please specify the original PR and why you need to backport that PR. If this PR will be backported please specify to which release cycle the backport is meant for:

Backport of #47672 to 15.0.x for data taking.

[fwyzard]

type bugfix

[fwyzard]

backport #47672

[fwyzard]

please test

[cmsbuild]

A new Pull Request was created by @fwyzard for CMSSW_15_0_X.

It involves the following packages:

• HeterogeneousCore/AlpakaCore (heterogeneous)

@cmsbuild, @fwyzard, @makortel can you please review it and eventually sign? Thanks.
@makortel, @missirol, @rovere this is something you requested to watch as well.
@antoniovilela, @mandrenguyen, @rappoccio, @sextonkennedy you are the release manager for this.

cms-bot commands are listed here

• Backported from AlpakaServiceSerialSync should always be available #47672

[cmsbuild]

cms-bot internal usage

[cmsbuild]

+1

Size: This PR adds an extra 20KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-ea03bc/45163/summary.html
COMMIT: a50a1ba
CMSSW: CMSSW_15_0_X_2025-03-23-2300/el8_amd64_gcc12
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/47673/45163/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially removed 2 lines from the logs
• Reco comparison results: 4 differences found in the comparisons
• DQMHistoTests: Total files compared: 50
• DQMHistoTests: Total histograms compared: 3999716
• DQMHistoTests: Total failures: 66
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3999630
• DQMHistoTests: Total skipped: 20
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 49 files compared)
• Checked 218 log files, 189 edm output root files, 50 DQM output files
• TriggerResults: no differences found

[fwyzard]

+heterogeneous

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_15_0_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_15_1_X is complete. This pull request will now be reviewed by the release team before it's merged. @mandrenguyen, @rappoccio, @sextonkennedy, @antoniovilela (and backports should be raised in the release meeting by the corresponding L2)

[mandrenguyen]

+1