[IntentHandling] Extend the app-service-intent-handling flag to 87.

This CL extends the app-service-intent-handling flag to 87 because it
was just turned on by default for one milestone.

BUG=853604

Change-Id: I6838130f223d1487610d193f9257635bcdaf009e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2367426Reviewed-by: Dominick Ng <dominickn@chromium.org>
Commit-Queue: Maggie Cai <mxcai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800513}

chrome/browser/flag-metadata.json

@@ -141,7 +141,7 @@
   {
     "name": "app-service-intent-handling",
     "owners": [ "chromeos-apps-foundation-team@google.com" ],
-    "expiry_milestone": 85
+    "expiry_milestone": 87
   },
   {
     "name": "arc-application-zoom",