[JENKINS-60434] Control pausing pipeline builds during quieting down period

[TueDissingWork]

Change description

Adding a few new features as well as the needed configuration parameters:

• control whether or not to pause pipeline builds during quieting down period
• toggle whether or not to abort long running builds during quieting down period
  • adding a config parameter to control the length of timeout in minutes
• default behaviour are unchanged

The feature implemented in this PR relates to the discussion in JENKINS-60434

The motivation for this change

We a running a large amount of individual Jenkins instances. That all run in Kubernetes. These are orchestrated by the Jenkins Operator and when a restart is needed by a reconcile loop, the operator does not wait for builds to finish -> causing abandoned build agents.

With this change it will be possible to introduce a grace period (the timeout) in which remaining builds can finish their work. When this grace period is over, any remaining builds will be aborted. This drains all nodes and makes it possible to perform a clean shutdown of Jenkins.

Testing done

Added a couple of new test cases that run through the different scenarios.

Also performed additional manual tests to ensure that the desired behaviour persists when running with build agents in Kubernetes.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[TueDissingWork]

This is a more elaborated version of the solution proposed in the PR: #846

[TueDissingWork]

a review or a comment on the work we be great :-)

[jglick]

On my list, but there is a lot on my list.