Add amphora failover API test

This patch adds the amphora failover API test.

This patch also improves the load balancer failover API test to validate
that the amphora IDs have changed. This was a TODO in the code waiting
for the amphora show service client to be completed.

Change-Id: Ibffeb959d88b36be26355ff1b6a96dde8cfcd8c8
Story: 2004852
Task: 29077
2 files changed