waffle: Stop tying shuffle seed to the milestone

We previously made some changes to stop re-populating the keywords
database on milestone changes. This makes the rotation of the shuffle
seed unnecessary as well, so this CL removes this and the associated
profile pref storing the shuffle milestone.

Bug: b:340412113
Bug: b:361013517
Change-Id: I95c840138ae706a21a00428dacbf784bfd6c06ed
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6433678
Commit-Queue: Tomasz Wiszkowski <[email protected]>
Reviewed-by: Ted Choc <[email protected]>
Auto-Submit: Nicolas Dossou-Gbété <[email protected]>
Reviewed-by: Tomasz Wiszkowski <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1442781}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 7faca474..a29d593f 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -1085,6 +1085,10 @@
 inline constexpr char kRecurrentSSLInterstitial[] =
     "profile.ssl_recurrent_interstitial";
 
+// Deprecated 04/2025.
+inline constexpr char kDefaultSearchProviderChoiceScreenShuffleMilestone[] =
+    "default_search_provider.choice_screen_shuffle_milestone";
+
 // Register local state used only for migration (clearing or moving to a new
 // key).
 void RegisterLocalStatePrefsForMigration(PrefRegistrySimple* registry) {
@@ -1517,6 +1521,10 @@
 
   // Deprecated 03/2025
   registry->RegisterDictionaryPref(kRecurrentSSLInterstitial);
+
+  // Deprecated 04/2025.
+  registry->RegisterIntegerPref(
+      kDefaultSearchProviderChoiceScreenShuffleMilestone, 0);
 }
 
 }  // namespace
@@ -2790,6 +2798,9 @@
   // Added 03/2025.
   profile_prefs->ClearPref(kRecurrentSSLInterstitial);
 
+  // Added 04/2025.
+  profile_prefs->ClearPref(kDefaultSearchProviderChoiceScreenShuffleMilestone);
+
   // Please don't delete the following line. It is used by PRESUBMIT.py.
   // END_MIGRATE_OBSOLETE_PROFILE_PREFS