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>

Change-Id: Ibfa83d0b5b93680890aad8c88c041fa344765448
Refactor CIDR field to use netaddr.IPNetwork

This makes the CIDR field become the IPNetwork field (and associate
versioned fields). It also uses the netaddr.IPNetwork class, which
is what should have been done in the first place.

Wire format is unchanged, so we can make this without any version
bumps or upgrade impact.

Related to blueprint nova-network-objects

Change-Id: I1a3ab6a5f4c624f3da0ab1c78c75c6f1e474541f
xenapi: stop server destroy on live_migrate errors

Currently where there are errors after live-migration has completed, the
server is destroyed, which for XenAPI driver, means the server no longer
exists, because XenServer has already deleted the source VM.

Closes-Bug: #1262206
Change-Id: I7f827f5d972da26f5d1edae7a22fb45a1f5dd6ca
Merge "Refactor CIDR field to use netaddr.IPNetwork"
Merge "VMware: unnecessary session reconnection"
Merge "xenapi: stop server destroy on live_migrate errors"