Add caller to v1 image_client wait_for_image_status timeout exception

This will help in fingerprinting race failures with logstash so that we
can uniquely identify the same error message but between different tests
that are failing, then we can see trends over time.

Related-Bug: #1289546

Change-Id: Iaeeaef6f9235cd8c6f7fa4dae3424542b708ad2b
1 file changed