Update enable-mark-http-as flag expiry

This bumps the expiry for enable-mark-http-as from M80 to M86.

Change-Id: Ie682789e5a595e8ab614c4993694291fab43119a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1919435Reviewed-by: Livvie Lin <livvielin@chromium.org>
Commit-Queue: Christopher Thompson <cthomp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#715813}

chrome/browser/flag-metadata.json

@@ -1524,7 +1524,7 @@
   {
     "name": "enable-mark-http-as",
     "owners": [ "cthomp", "estark" ],
-    "expiry_milestone": 80
+    "expiry_milestone": 86
   },
   {
     "name": "enable-md-rounded-corners-on-dialogs",