refactor: resume a paused build when it is aborted

[bianbbc87]

Describe PR

CpsFlowExecution.interrupt() delivers a FlowInterruptedException into the CPS threads, but propagating it running catch/finally and ending the program requires CpsThreadGroup.run(), which scheduleRun() skips while paused.

So if the build stayed paused, the abort was delivered but never completed until someone unpaused it manually or used Hard Kill.

This just adds one rule on top aborting a build clears the pause. The pause gate itself is untouched.
Quiet-down pauses and CpsBodyExecution.cancel() (parallel failFast) are out of scope.

Fixes #1818

Testing done

New test CpsFlowExecutionTest.abortWhilePaused pauses a build at semaphore, aborts it, and checks it finishes. Pipeline is try {semaphore 'wait'} finally {echo 'cleaning up'}.

mvn -pl plugin -am test -Dtest=CpsFlowExecutionTest#abortWhilePaused

Before fix

[p #1] Pausing
SemaphoreStep$Execution#stop: Stopping wait/1
[p #1] Click here to forcibly terminate running steps
=> ConditionTimeoutException: build still running after 60s

After fix

[p #1] Pausing
SemaphoreStep$Execution#stop: Stopping wait/1
[p #1] Resuming to process abort
[p #1] cleaning up
[p #1] Finished: ABORTED

Expected result

the abort completes instead of hanging, finally still runs, and the build ends as ABORTED.

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