NetworkService: Change the ForceNetworkInProcess removal plan

Update the plan to remove it at m84. This is because there is
an agreement that 4 milestones notice will be provided prior
to removing the policy.

https://www.chromium.org/Home/third-party-developers

Bug: 1036230
Change-Id: I7e8a710a116df37ea6099a2036f7f471b4394f86
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2022363
Auto-Submit: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Commit-Queue: Takashi Toyoshima <toyoshim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735763}

components/policy/resources/policy_templates.json

@@ -17471,7 +17471,7 @@
 
       If this policy is not set, networking code will run out of the browser process by default.
 
-      This policy will be removed in <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> version 82.''',
+      This policy will be removed in <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> version 84.''',
     },
     {
       'name': 'VoiceInteractionContextEnabled',