[Stable Only] Enforce policy for qos_policy_id attribute

Currently while updating 'qos_policy_id', authorization policies
are not enforced and as a result it can be set or unset over
port/network/fip by an unauthorized user.

This patch fixes it by setting 'enforce_policy' to True
for this attribute for Floating IP, for port and network
it's fixed in neutron-lib[1].

This patch is only for stable releases as for releases since
Yoga this is fixed in neutron-lib[2] itself.

[1] https://review.opendev.org/q/Ieee1ca092e572ad4696105962fbc6de675454657
[2] https://review.opendev.org/c/openstack/neutron-lib/+/825088

Closes-Bug: #1957175
Change-Id: Ie0660e5e89e45c00b79464368ba337d27a824714
(cherry picked from commit 0c2af0f6e7)

neutron/extensions/qos_fip.py

@@ -24,6 +24,7 @@ EXTENDED_ATTRIBUTES_2_0 = {
             'allow_put': True,
             'is_visible': True,
             'default': None,
+            'enforce_policy': True,
             'validate': {'type:uuid_or_none': None}}
     }
 }

releasenotes/notes/bug-1957175-764bc9c73b8d46e9.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Enforce policy for 'qos_policy_id' attribute of
+    Floating IP so only authorized users can set/unset it.
+    For more info see `bug LP#1957175 <https://bugs.launchpad.net/bugs/1957175>`_.