TestAgentController really runs the controller and evaluates multiple
calls to the controller's Sync with real informers caching updates.
There is a large amount of non-determinism in this unit test, and it
does not always behave the same way. Because it makes assertions about
the specific errors that should be returned by Sync, it was not
accounting for some errors that are only returned by Sync once in a
while depending on the exact (unpredictable) order of operations.
This commit doesn't fix the non-determinism in the test, but rather
tries to work around it by also allowing other (undesired but
inevitable) error messages to appear in the list of actual error
messages returned by the calls to the Sync function.
Signed-off-by: Margo Crawford <margaretc@vmware.com>