Make the wait_for_server_status timeout message a bit more clear

The current error message when wait_for_server_status times out only
includes the vm_state but the method, by default, is really waiting for
a state combination of vm_state/task_state.

Sometimes the vm_state is the desired status but the task_state is not,
for example:

"Server 613b9fd8-9f3f-41a6-86cc-a36301aa7fc8 failed to reach ACTIVE
status within the required time (196 s). Current status: ACTIVE."

This patch adds the current task_state to the error message for clarity
when the timeout occurs.

Related-Bug: #1257561

Change-Id: Icfce12035bf4938eac3a13a7b640db4398ef832f
1 file changed