rgw: don't use merge_and_store_attrs() when recreating a bucket

rgw: don't use merge_and_store_attrs() when recreating a bucket

https://github.com/ceph/ceph/pull/56583 recently fixed
merge_and_store_attrs() to preserve existing attrs, but this broke the
swift api's ability to remove container metadata. RGWCreateBucket
handles this merging itself with prepare_add_del_attrs(), so we should
just assign createparams.attrs to the bucket and store it with
bucket->put_info()

make the same change for RGWPutMetadataBucket which swift uses to
add/remove existing metadata

Fixes: https://tracker.ceph.com/issues/69301
Signed-off-by: Casey Bodley <cbodley@redhat.com>