Use safe_setup instead try block in setUpClass

To avoid resource leakage in case of exception in setUpClass,
some tests have try catch block in setUpClass and call tearDownClass
explicitly.
safe_setup decorator is for same purpose which should be
used instead.

Change-Id: I59372ec96dcec0058d30e503b22540ce09c43d43
Merge "Use safe_setup instead try block in setUpClass"