Description of problem:
If we have  local rgw user and an LDAP user with the same name then RGW doesn't differentiate between them. so a bucket created by local user will be visible to ldap user. Not sure is this expected behaviour else it will be a security flaw.

Version-Release number of selected component (if applicable):
10.2.2-24redhat1xenial

How reproducible:
Always


Steps to Reproduce:
1.configure rgw , created a local user with name "user1" and create few buckets with keys
2.setup ldap and create an user with same name "user1"
3.from s3 api authenticate ldap user "user1" and try to list buckets

Actual results:
All the buckets of local rgw user "user1" will be listed even though we have userd ldap user's key