Update expiry for manual password generation flag

Change-Id: Ib0cdf0c62cc391934d37554274a321bd93f4d364
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1865341
Commit-Queue: Ioana Pandele <ioanap@chromium.org>
Commit-Queue: Friedrich [CET] <fhorschig@chromium.org>
Auto-Submit: Ioana Pandele <ioanap@chromium.org>
Reviewed-by: Friedrich [CET] <fhorschig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706837}

chrome/browser/flag-metadata.json

@@ -2382,7 +2382,7 @@
   {
     "name": "manual-password-generation-android",
     "owners": [ "ioanap" ],
-    "expiry_milestone": 78
+    "expiry_milestone": 80
   },
   {
     "name": "media-router-cast-allow-all-ips",