[Android] increase detailed-language-settings flag expiry

This CL moves the expiry on the detailed-language-settings flag from
M89 to M91.

Bug: 1127531
Change-Id: I23d2df7e3a2b87a45bc8c87baafb45589dee4b4a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2626977Reviewed-by: Megan Jablonski <megjablon@chromium.org>
Commit-Queue: Trevor  Perrier <perrier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843308}

chrome/browser/flag-metadata.json

@@ -102,7 +102,7 @@
   {
     "name": "android-detailed-language-settings",
     "owners": [ "perrier", "chrome-langauge@google.com" ],
-    "expiry_milestone": 89
+    "expiry_milestone": 91
   },
   {
     "name": "android-managed-by-menu-item",