Remove redundant enforceCallingPermission()

This CL aims to simplify security checks for

  IInputMethodManager#onShellCommand().

Basically the calling UID check [1] remains to be the main security
policy for that IPC method.  Context#enforceCallingPermission() checks
added in later CLs [2][3] are just redundant with an assumption that
the shell package has those permissions.

For simplicity and readability, let's keep only the most relevant
security check for IMMS#onShellCommand() method.

 [1]: If87189563ccaacd4f9c666bab4f9ad08a9343084
      b8d240fa3f
 [2]: I6fd47b5cc1e7da7222774df20247a2c69a70f45b
      db25df71be
 [3]: If91137e0c144d90ac3046f30607e36bb957a7e0e
      8a2b96bb0a

Bug: 34886274
Test: atest CtsInputMethodServiceHostTestCases:ShellCommandFromAppTest
Change-Id: I19a6833bb7ff6100d4e9428243005377a7fbf432

services/core/java/com/android/server/inputmethod/InputMethodManagerService.java

@@ -64,7 +64,6 @@ import android.annotation.EnforcePermission;
 import android.annotation.IntDef;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
-import android.annotation.RequiresPermission;
 import android.annotation.UiThread;
 import android.annotation.UserIdInt;
 import android.app.ActivityManager;
@@ -5879,22 +5878,10 @@ public final class InputMethodManagerService extends IInputMethodManager.Stub
             mService = service;
         }
 
-        @RequiresPermission(allOf = {
-                Manifest.permission.DUMP,
-                Manifest.permission.INTERACT_ACROSS_USERS_FULL,
-                Manifest.permission.WRITE_SECURE_SETTINGS,
-        })
         @BinderThread
         @ShellCommandResult
         @Override
         public int onCommand(@Nullable String cmd) {
-            // For shell command, require all the permissions here in favor of code simplicity.
-            Arrays.asList(
-                    Manifest.permission.DUMP,
-                    Manifest.permission.INTERACT_ACROSS_USERS_FULL,
-                    Manifest.permission.WRITE_SECURE_SETTINGS
-            ).forEach(permission -> mService.mContext.enforceCallingPermission(permission, null));
-
             final long identity = Binder.clearCallingIdentity();
             try {
                 return onCommandWithSystemIdentity(cmd);