Update expiry milestone for privacy-settings-redesign

Work is continuing using the privacy-settings-redesign flag on TOT, so we are extending the expiry of the flag by two milestones.

Bug: 1032584
Change-Id: Ic47a7b4b349b0fd12cd00c0cb90774d36d210d1e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2153163Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Commit-Queue: Sean Harrison <harrisonsean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760478}

chrome/browser/flag-metadata.json

@@ -3429,7 +3429,7 @@
     "name": "privacy-settings-redesign",
     "owners": ["harrisonsean", "msramek",
       "chrome-friendly-settings@google.com"],
-    "expiry_milestone": 84
+    "expiry_milestone": 86
   },
   {
     "name": "proactive-tab-freeze",