Remove test_can_log_into_created_server

The nova v3 version of test_create_server still has the
test_can_log_into_created_server, and referencing to not existing
method.

Does not makes sense just testing the login alone, if we have lot of test
for testing many other ssh dependent things.
A basic remote command execution cost is close to just trying
to authenticate.

Change-Id: I0d53727934249f83cc562ab8e372aaffb4b1ac65
Implements: blueprint ssh-auth-strategy
Merge "Remove test_can_log_into_created_server"