Attempt v2 of "Disables non-system AccessibilityMenu for secondary users."

Re-landing of commit 43cd49fa85
but uses createContextAsUser instead of createPackageContextAsUser.
createPackageContextAsUser looks up the package info for non-system
packages, which caused a boottime regression for A11yManagerService
from 5ms to ~40ms. This new version has no regression and functions
the same for our purposes.

Bug: 284196235
Test: Create secondary user, observe only one Accessibility Menu entry
      in Settings > Accessibility.
Test: v2/android-crystalball-eng/asit/perf/boottime_test
      locally and with go/abtd
Change-Id: I8410d818891690d9d3307897b168b94125d41b16

services/accessibility/java/com/android/server/accessibility/AccessibilityManagerService.java

@@ -958,7 +958,13 @@ public class AccessibilityManagerService extends IAccessibilityManager.Stub
         final ComponentName menuToMigrate =
                 AccessibilityUtils.getAccessibilityMenuComponentToMigrate(mPackageManager, userId);
         if (menuToMigrate != null) {
-            mPackageManager.setComponentEnabledSetting(
+            // PackageManager#setComponentEnabledSetting disables the component for only the user
+            // linked to PackageManager's context, but mPackageManager is linked to the system user,
+            // so grab a new PackageManager for the current user to support secondary users.
+            final PackageManager userPackageManager =
+                    mContext.createContextAsUser(UserHandle.of(userId), /* flags = */ 0)
+                            .getPackageManager();
+            userPackageManager.setComponentEnabledSetting(
                     menuToMigrate,
                     PackageManager.COMPONENT_ENABLED_STATE_DISABLED,
                     PackageManager.DONT_KILL_APP);
@@ -1845,6 +1851,9 @@ public class AccessibilityManagerService extends IAccessibilityManager.Stub
             // find out a way to detect the device finished the OTA and switch the user.
             migrateAccessibilityButtonSettingsIfNecessaryLocked(userState, null,
                     /* restoreFromSdkInt = */0);
+            // Package components are disabled per user, so secondary users also need their migrated
+            // Accessibility Menu component disabled.
+            disableAccessibilityMenuToMigrateIfNeeded();
 
             if (announceNewUser) {
                 // Schedule announcement of the current user if needed.