Nicer build log message when ExecutorPickle fails to resume

[jglick]

#47 (comment)

In

workflow-durable-task-step-plugin/src/test/java/org/jenkinsci/plugins/workflow/support/pickles/ExecutorPickleTest.java

Lines 141 to 144 in 65a4f98

	Thread.sleep(ExecutorPickle.TIMEOUT_WAITING_FOR_NODE_MILLIS + 1000L);
	Assert.assertEquals("Should have given up and killed the Task representing the resuming build", 0, Queue.getInstance().getItems().length );
	Assert.assertFalse(run.isBuilding());
	j.assertBuildStatus(Result.FAILURE, run);

Before:

[p #1] ERROR: Killed hudson.model.Queue$BuildableItem:ExecutorStepExecution.PlaceholderTask{runId=p#1,label=slave0,context=CpsStepContext[3:node]:Owner[p/1:p #1],cookie=1f900f85-0501-4f30-83d9-4a8a9ed1f70a,auth=null}:3 after waiting for 15,000 ms because we assume unknown Node slave0 is never going to appear!

After:

[p #1] ERROR: Killed part of p #1 after waiting for 15,000 ms because we assume unknown Node slave0 is never going to appear!

[jglick]

@car-roll this is more enhancement than chore I think?