qa/rgw: use 'with-sse-s3' override for s3tests

qa/rgw: use 'with-sse-s3' override for s3tests

don't rely on the ceph manager task to parse a config file. each rgw
could be using a different config. instead, revert to an s3tests
override called 'with-sse-s3'

this way, the only job that enables sse-s3, vault_transit.yaml, contains
both the 'rgw crypt sse s3' configurables, and the flag to enable the
associated test cases

Signed-off-by: Casey Bodley <cbodley@redhat.com>