Extend the flags for Desktop HaTS survey triggers to M90

Since we plan to reuse these triggers for another round of surveys soon.

Bug: None
Change-Id: I7ad17f483288afbac90955ca1a24e21fd9973397
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2421489Reviewed-by: Sean Harrison <harrisonsean@chromium.org>
Commit-Queue: Martin Šrámek <msramek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808924}

chrome/browser/flag-metadata.json

@@ -2763,12 +2763,12 @@
   {
     "name": "happiness-tracking-surveys-for-desktop-settings",
     "owners": [ "msramek", "chrome-friendly-settings@google.com" ],
-    "expiry_milestone": 86
+    "expiry_milestone": 90
   },
   {
     "name": "happiness-tracking-surveys-for-desktop-settings-privacy",
     "owners": [ "msramek", "chrome-friendly-settings@google.com" ],
-    "expiry_milestone": 86
+    "expiry_milestone": 90
   },
   {
     "name": "hardware-media-key-handling",