Use a vanity URL for redirect uri so that it does not conflict with
existing keystone endpoint. The documentation was updated recently[1]
but the actual configuration used in devstack setup was still kept old
at that time.
[1] 7ac0c3cd33
Related-Bug: #2075349
Change-Id: I8d06f3c388260f356c7a1da0212bb3b399f3a848
(cherry picked from commit c450599cbd)
47891f4ae8