A couple tests require lowering the grace period to keep the test from
taking the full 30s timeout.
The Retry_hang test also needed to be removed from the Parallel group,
becuase it modifies the global refreshGracePeriod variable.
This test unfortunately relies on the timing of the loops in
WaitForState, and the text of the error message. Adjust the timing so
the timeout isn't an even multiple of the poll interval, and make sure
we reach a minimum number of retries.
Sometimes when waiting on a target state, the set of valid states
through which a value will transition is unknown. This commit adds
support for an empty Pending slice and will treat any states that are not
the target as valid provided the timeouts are not exceeded.
