radosgw-admin as of Octopus uses a different time format, it uses
"2006-01-02T15:04:05.999999999Z". It's close from RFC3339 but not quite
the same. This change is needed in order for the operator image (with a
Ceph Octopus based image) to perform radosgw-admin call correctly.
Signed-off-by: Sébastien Han <seb@redhat.com>