In some cases on Arista VXLAN fabrics, VMs are inaccessible via network
after live migration, despite garps being observed on the fabric itself.
This patch builds on the feature
``[workarounds]/enable_qemu_monitor_announce_self`` feature as reported
in `bug 1815989 <https://bugs.launchpad.net/nova/+bug/1815989>`
This patch adds the ability to config the number of times the QEMU
announce_self monitor command is called, and add a new configuration option to
specify a delay between calling the announce_self command multiple times,
as in some cases, multiple announce_self monitor commands are required for
the fabric to honor the garp packets and the VM to become accessible via
the network after live migration.
Closes-Bug: #1996995
Change-Id: I2f5bf7c9de621bb1dc7fae5b3374629a4fcc1f46
fba851bf3a