This builds on I0bd63b655ad3d3d39af8d15c781ce0a45efc8e3a
which made DELETE /os-services/{service_id} fail with a 409
response if the host has instances on it. This change checks
for in-progress migrations involving the nodes on the host,
either as the source or destination nodes, and returns a 409
error response if any are found.
Failling to do this can lead to orphaned resource providers
in placement and also failing to properly confirm or revert
a pending resize or cold migration.
A release note is included for the (justified) behavior
change in the API. A new microversion should not be required
for this since admins should not have to opt out of broken
behavior.
Change-Id: I70e06c607045a1c0842f13069e51fef438012a9c
Closes-Bug: #1852610
92fed02610