[Build] Adapt to move of SWT's build pipeline to 'releng' Jenkins

[HannesWell]

Fixes #531

Lets see if this helps already.

[github-actions]

Test Results

     303 files       303 suites   5m 58s ⏱️
  4 047 tests   4 035 ✔️   8 💤 3 ❌ 1 🔥
12 068 runs  11 993 ✔️ 70 💤 4 ❌ 1 🔥

For more details on these failures and errors, see this check.

Results for commit b2b4391.

♻️ This comment has been updated with latest results.

[iloveeclipse]

Hangs:

Pull request #533 opened
02:54:58 Connecting to https://api.github.com/ using GitHub bot (username/token)
Connecting to https://api.github.com/ to check permissions of obtain list of HannesWell for eclipse-platform/eclipse.platform.swt
Obtained Jenkinsfile from c02759d53bf142b2705f3a93f27a0e36d77860e4
[Pipeline] Start of Pipeline
[Pipeline] echo
[WARNING] label option is deprecated. To use a static pod template, use the 'inheritFrom' option.
[Pipeline] podTemplate
[Pipeline] {
[Pipeline] node
Still waiting to schedule task
‘[swtbuild-pod-8z9j2-53cgc](https://ci.eclipse.org/releng/computer/swtbuild-pod-8z9j2-53cgc/)’ is offline

[HannesWell]

Hangs:

Yes :/ I compared the JIRO definitions of the eclipse.platform and eclipse.platform.releng Jenkins

• https://github.com/eclipse-cbi/jiro/blob/master/instances/eclipse.platform/config.jsonnet
• https://github.com/eclipse-cbi/jiro/blob/master/instances/eclipse.platform.releng/config.jsonnet

and created eclipse-cbi/jiro#260 from it. Maybe we are lucky and that would solve the issue or infra-team can help us to find a better solution.

[HannesWell]

After @pstankie's help, see https://gitlab.eclipse.org/eclipsefdn/helpdesk/-/issues/2526#note_1067005, the build now 'succeeds' as unstable. Thanks for that!

There is only one test-failure, which also fails in the GH-workflow builds and used to fail (sometimes) in the platform JIPP (https://ci.eclipse.org/platform/job/eclipse.platform.swt/job/master/). In general I think those failures should be eliminated.
But this change has only the purpose to fix the build and is therefore good to go.

[HannesWell]

Created https://gitlab.eclipse.org/eclipsefdn/helpdesk/-/issues/2546 to ask the infra-team to install the required plug-ins for the releng JIPP too.