Reverting our test runner's background building behaviour.

Our continuous build has been failing to complete lately. See:
http://jwilson.mtv.corp.google.com:8080/job/master_passion/274/consoleFull

In addition to this problem the continuous build is compiling many
more tests ahead-of-time than we were originally - previously we
would only have up to 4 tests ready-to-run at any given time. With
this change the ExecutorCompletionService was building and installing
all of the tests eagerly.

I believe the problem might be a mismatch between how the BlockingQueue
and the ExecutorCompletionService select which order to return futures.
By removing the ExecutorCompletionService I remove the opportunity for
such a conflict!
1 file changed