Extend flags account-id-migration and use-multilogin-endpoint to M92

This CLs extends flags account-id-migration and use-multilogin-endpoint
until M92 as they are still not fully rolled out.

Bug: None
Change-Id: If2d0a2b4fa5fc0f32930eff1ea0267862a924456
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2593104
Commit-Queue: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: David Roger <droger@chromium.org>
Auto-Submit: Mihai Sardarescu <msarda@chromium.org>
Reviewed-by: David Roger <droger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837527}

chrome/browser/flag-metadata.json

@@ -41,7 +41,7 @@
   {
     "name": "account-id-migration",
     "owners": [ "msarda" ],
-    "expiry_milestone": 88
+    "expiry_milestone": 92
   },
   {
     "name": "account-management-flows-v2",
@@ -4895,7 +4895,7 @@
   {
     "name": "use-multilogin-endpoint",
     "owners": [ "droger", "msarda" ],
-    "expiry_milestone": 88
+    "expiry_milestone": 92
   },
   {
     "name": "use-of-hash-affiliation-fetcher",