VMware: unnecessary session reconnection

An error FAULT_NOT_AUTHENTICATED could imply that there is a problem
with the backend or that no values were found (for example there are
no running VMS). In the latter case the connection should not
be restarted.

The patch also ensures that the session is restarted if there are
connection issues.

This issue occasionally causes CI issues with minesweeper.

Closes-bug: #1265512

Co-authored-by: Shawn Harsock <hartsocks@vmware.com>

Conflicts:

	nova/tests/virt/vmwareapi/test_vmwareapi.py

Change-Id: Ibfa83d0b5b93680890aad8c88c041fa344765448
(cherry picked from commit 55296828a7d7a03736a21d846da15571ca22ec9e)
Merge "VMware: unnecessary session reconnection" into stable/havana