Cleanup try/except/finally blocks in several tests

There are several tests that have large try/except blocks which catch
Exception and then log their own error message but don't include the
original exception message. Some of these also have finally blocks doing
cleanup which could be performed with a call to self.addCleanup in the
test itself. Since this patch removes the useless self.fail with a
custom message masking the original exception, I also refactored the
finally blocks to use addCleanup instead.

Fixes bug 1207893

Change-Id: I6e9532e5067bbc0458ed3dc3faac58151aa696a0