rgw: remove prefix & delim params for bucket removal & mp upload abort

rgw: remove prefix & delim params for bucket removal & mp upload abort

The calls to remove a bucket had parameters to specify a prefix and
delimiter, which does not make sense. This was precipitated due to some
existing Swift protocol logic, but buckets are removed irrespective of
prefix and delimiter. So the functions and calls are adjusted to
remove those parameters. Additionally, those same parameters were
removed for aborting incomplete multipart uploads.

Additionally a bug is fixed in which during bucket removal, multipart
uploads were only removed if the prefix was non-empty.

Signed-off-by: J. Eric Ivancich <ivancich@redhat.com>