Pool test cleanups and reliability PYTHON-436
Pool test cleanups and reliability PYTHON-436

* Shorter thread-join timeout: If a test will fail, take 5 seconds to do so instead of 300.
* Delete unnecessary asserts.
* More reliable test_over_max_times_out.
* Skip a deadlocking test on Jython.

ShaneHarvey/mongo-python-driver,jameslittle/mongo-python-driver,bq-xiao/mongo-python-driver,ameily/mongo-python-driver,mongodb/mongo-python-driver,gormanb/mongo-python-driver,ramnes/mongo-python-driver,ultrabug/mongo-python-driver,ameily/mongo-python-driver,ShaneHarvey/mongo-python-driver,macdiesel/mongo-python-driver,jameslittle/mongo-python-driver,brianwrf/mongo-python-driver,aherlihy/mongo-python-driver,gormanb/mongo-python-driver,bq-xiao/mongo-python-driver,mongodb/mongo-python-driver,felixonmars/mongo-python-driver,rychipman/mongo-python-driver,inspectlabs/mongo-python-driver,develf/mongo-python-driver,mongodb/mongo-python-driver,pigate/mongo-python-driver,llvtt/mongo-python-driver,ShaneHarvey/mongo-python-driver,inspectlabs/mongo-python-driver,WingGao/mongo-python-driver,brianwrf/mongo-python-driver,aherlihy/mongo-python-driver,pigate/mongo-python-driver,develf/mongo-python-driver,aherlihy/mongo-python-driver,macdiesel/mongo-python-driver,ramnes/mongo-python-driver,llvtt/mongo-python-driver,WingGao/mongo-python-driver,ramnes/mongo-python-driver,rychipman/mongo-python-driver,ultrabug/mongo-python-driver,felixonmars/mongo-python-driver