Move InvalidServiceTag

We are going to make test.py stable for plugins, so it should
only depend on tempest.lib and config.

InvalidServiceTag is in the exceptions module.
It cannot be moved in tempest.lib.exceptions since it has no meaning
in there, so moving it to test.py directly.

Change-Id: I969fb45a44ce08c176d64dfe1c58d75215eacdf5
3 files changed