Remove note about per-network FT switch

The switch no longer exists.

Bug: b:172071699
Change-Id: Ic6bcf63de7acb1847d40fa5d5caab932e2d90ae5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2514761Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Pavol Marko <pmarko@chromium.org>
Commit-Queue: Matthew Wang <matthewmwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823624}

components/policy/resources/policy_templates.json

@@ -14584,9 +14584,7 @@
       'caption': '''Enable 802.11r Fast Transition''',
       'desc': '''Setting the policy to Enabled means that Fast Transition is used when the wireless access point supports it. It applies to all users and interfaces on the device.
 
-      Setting the policy to Disabled or leaving it unset means that Fast Transition isn't used.
-
-      Note: To use Fast Transition, also turn on the per-network ONC property.''',
+      Setting the policy to Disabled or leaving it unset means that Fast Transition isn't used.''',
       'type': 'main',
       'schema': { 'type': 'boolean' },
       'supported_on': ['chrome_os:72-'],