Internal clients used to retry operations even on client errors, where
we had no expectation that we would get a different response. Among
other things, this would cause container-sync to needlessly retry
deletes that would 404, even though we had code specifically in place to
say that 404s are OK.
While we're at it, also flag 409s as being OK (since the remote has
newer data than us).
Change-Id: I1833a8ff2ac2f4126b6274d6bba47e2b58a41745
Closes-Bug: #1849841
f68e22d43a