[ExploreSites[: Extend explore sites flag by 10 milestones

Change-Id: I7cbf3a5c94f0d5f43dc0c2e08a7832a5fc6af21c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2415538Reviewed-by: Justin DeWitt <dewittj@chromium.org>
Commit-Queue: Cathy Li <chili@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808055}

chrome/browser/flag-metadata.json

@@ -2476,7 +2476,7 @@
   {
     "name": "explore-sites",
     "owners": [ "chili", "dewittj" ],
-    "expiry_milestone": 85
+    "expiry_milestone": 95
   },
   {
     "name": "extend-open-in-files-support",