Correctly call client inits from test_multi_backend

This commit fixes the client init calls in setUpClass for
test_mult_backend. Since this doesn't run in the gate it slipped through
the massive config refactor.

Closes-Bug: #1276215

Change-Id: Ibcd521a5b5c3f4d755387b29ee73dcc042c44fa0
Merge "Correctly call client inits from test_multi_backend"