Add a timeout for pickle resolution to prevent indefinitely stuck builds

[dwnusbaum]

Related to jenkinsci/workflow-api-plugin#357 and jenkinsci/workflow-api-plugin#347. Even though the fix there should prevent stuck builds from leaking memory of other builds, it is still worth trying to prevent builds from getting stuck in the first place.

This PR adds a hard timeout to pickle resolution. I do not care much about the exact timeout, I just want to pick a value that doesn't break pickle resolution in non-pathological cases. The case described in jenkinsci/workflow-api-plugin#357 involved a build repeatedly resuming and trying to resolve a FilePathPickle that was never going to come back for around a month.

If preferred this could be done in CpsFlowExecution.loadProgramAsync or TryRepeatedly instead.

Testing done

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[dwnusbaum]

Not sure what value is best here. One hour resolving pickles seemed roughly ok to me. I think we don't really expect TryRepeatedly to be used normally anyway now that ExecutorStepDynamicContext and FilePathDynamicContext exist, but there are a couple of other usages.