rgw: Ensure buckets too old to decode a layout have layout logs

rgw: Ensure buckets too old to decode a layout have layout logs

When decoding `RGWBucketInfo` data from before Pacific, we won't call
`rgw::BucketLayout::decode`, but will instead synthesize the layout
information. This leaves the `rgw::BucketLayout::logs` empty, as the
fallback to populate it only applies to old versions of
`rgw::BucketLayout`.

Add a check at the end of `RGWBUcketInfo::decode` to populate it if
empty.

Fixes: https://tracker.ceph.com/issues/53132
Signed-off-by: Adam C. Emerson <aemerson@redhat.com>