Lower per-app notificationchannel limit

Test: PreferencesHelperTest
Bug: 240422263
Change-Id: I8c12e3fc73e4a88842af275feaf2acffcced0402
diff --git a/services/core/java/com/android/server/notification/PreferencesHelper.java b/services/core/java/com/android/server/notification/PreferencesHelper.java
index 477b8da..d8aa469 100644
--- a/services/core/java/com/android/server/notification/PreferencesHelper.java
+++ b/services/core/java/com/android/server/notification/PreferencesHelper.java
@@ -106,7 +106,7 @@
     private static final String NON_BLOCKABLE_CHANNEL_DELIM = ":";
 
     @VisibleForTesting
-    static final int NOTIFICATION_CHANNEL_COUNT_LIMIT = 50000;
+    static final int NOTIFICATION_CHANNEL_COUNT_LIMIT = 5000;
     @VisibleForTesting
     static final int NOTIFICATION_CHANNEL_GROUP_COUNT_LIMIT = 50000;