TestEnv: Make sure self.conf and self.test_conf aren't None
TestEnv: Make sure self.conf and self.test_conf aren't None

This will allow us to simplify other code in following commits

joelagnel/lisa,arnoldlu/lisa,ARM-software/lisa,credp/lisa,ARM-software/lisa,ARM-software/lisa,mdigiorgio/lisa,arnoldlu/lisa,credp/lisa,bjackman/lisa,ARM-software/lisa,credp/lisa,joelagnel/lisa,credp/lisa,bjackman/lisa,mdigiorgio/lisa