Extend compute model attributes

This patch extends compute model attributes by
adding new fields to Instance element. Values are
populated by nova the collector, using the same
nova list call, but requires a more recent compute
API microversion.
A new config option was added to allow users to
enable or disable the extended attributes and it is
disable by default.
Configure prometheus-based jobs to run on newer version
of nova api (2.96) and enables the extended attributes
collection.

Implements: bp/extend-compute-model-attributes

Assisted-By: Cursor (claude-4-sonnet)

Change-Id: Ibf31105d780dce510a59fc74241fa04e28529ade
Signed-off-by: Douglas Viroel <viroel@gmail.com>

releasenotes/notes/bp-extend-compute-model-attributes-b56bc093e8637bb4.yaml

@@ -0,0 +1,14 @@
+---
+features:
+  - |
+    The compute model was extended with additional server attributes to provide
+    more detailed information about compute instances. These additions will
+    enable strategies to make more precise decisions by considering more server
+    placement constraints. The new attributes are ``flavor extra specs`` and
+    ``pinned availability zone``. Each new attribute depends on a minimal
+    microversion to be supported in nova and configured in the watcher
+    configuration, at ``nova_client`` section. Please refer to the nova api-ref
+    documentation for more details on which microversion is required:
+    https://docs.openstack.org/api-ref/compute/
+    A new configuration option was added to allow the user to enable or disable
+    the extended attributes collection, which is disabled by default.