Remove last slash in gnocchi service url

Url is returned from catalogue with trail slash, but gabbi tests cant
compare results when there are single slash in result and two slashes in
expected results.

Related-PROD: PRODX-7913
Change-Id: Ib3dda217f55d0c58391b35b06e0fe443109e223c
(cherry picked from commit 325f55ee24d777a339ce5fa6a2cd5a7909385f63)
1 file changed