[iOS] Extend Discover flag expiry milestones

Change-Id: I73da518624891215e68658cd8494c0ba3ed979a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3568962
Auto-Submit: Adam Arcaro <adamta@google.com>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/main@{#988514}

chrome/browser/flag-metadata.json

@@ -1950,7 +1950,7 @@
   {
     "name": "enable-disco-feed-endpoint",
     "owners": [ "adamta", "sczs" ],
-    "expiry_milestone": 101
+    "expiry_milestone": 106
   },
   {
     "name": "enable-discount-consent-v2",
@@ -1965,12 +1965,12 @@
   {
     "name": "enable-discover-feed-shorter-cache",
     "owners": [ "edchin", "adamta", "sczs" ],
-    "expiry_milestone": 101
+    "expiry_milestone": 106
   },
   {
     "name": "enable-discover-feed-static-resource-serving",
     "owners": [ "adamta", "sczs" ],
-    "expiry_milestone": 101
+    "expiry_milestone": 106
   },
   {
     "name": "enable-dns-proxy",