Don't swallow PolicyNotAuthorized for resize/reboot actions

Removes 'except Exception' lines in the api which were preventing
PolicyNotAuthorized exceptions from bubbling up and returning 403 to the
caller.  This addresses policy exceptions in confirmResize,
revertResize, and reboot.

The try block calls into the compute api which sends a cast to perform
to bulk of the work, so there is little chance of an exception bubbling
up which is not already being caught.

Removes a unit test for a condition that should not exist.

Bug 1170453

Change-Id: I516a19894ab3d183057c774e84c4faa7053a6463
Merge "Don't swallow PolicyNotAuthorized for resize/reboot actions"