Add test caller to test_server_cfn_init timeout error message

When test_server_cfn_init times out trying to reach the server IP the
error message is pretty useless as far as being able to fingerprint the
failure in logstash.

This adds the test caller to the timeout error message like have in the
common waiters code.

Related-Bug: #1374175

Change-Id: Idd225af4e30fd1ab94570ed29d76664826cf965a
Merge "Add test caller to test_server_cfn_init timeout error message"