This change fixes a race that can occur because we have multiple
writers with no leader election lock.
1. TestAPIServingCertificateAutoCreationAndRotation/automatic
expires the current serving certificate
2. CertsExpirerController 1 deletes expired serving certificate
3. CertsExpirerController 2 starts deletion of expired serving
certificate but has not done so yet
4. CertsManagerController 1 creates new serving certificate
5. TestAPIServingCertificateAutoCreationAndRotation/automatic
records the new serving certificate
6. CertsExpirerController 2 finishes deletion, and thus deletes the
newly created serving certificate instead of the old one
7. CertsManagerController 2 creates new serving certificate
8. TestAPIServingCertificateAutoCreationAndRotation/automatic keeps
running and eventually times out because it is expecting the
serving certificate created by CertsManagerController 2 to match
the value it recorded from CertsManagerController 1 (which will
never happen since that certificate was incorrectly deleted).
Signed-off-by: Monis Khan <mok@vmware.com>