Make every swift clients use expected_success

Based on an original work by Swapnil Kulkarni in
I6a5511969d0432345529da6cd82544d2f8187468

Partially Implements blueprint: client-checks-success

Change-Id: I80bc2c2723bfeabb35fafc2b5733800ab5449f8c
Merge "Make every swift clients use expected_success"