fix test_lifecycle_expiration_header_{put,head}
fix test_lifecycle_expiration_header_{put,head}

Primarily fixes the expiration header() verifier function
check_lifecycle_expiration_header, but also cleans up
prefix handling in setup_lifecycle_expiration().

Signed-off-by: Matt Benjamin <b5ea062884a8f3dc969ff57d1008615447c56296@redhat.com>

ceph/s3-tests,robbat2/s3-tests,robbat2/s3-tests,ceph/s3-tests