Remove redundant API

Now InputMethodService has been migrated to WindowProviderService.
We don't need to override isUiContext anymore.

Bug: 193247900
Test: presubmit
Change-Id: I1cb0f04aca02d0d2c623995666ce5315125a0b4a

core/api/current.txt

@@ -19696,7 +19696,6 @@ package android.inputmethodservice {
   public abstract class AbstractInputMethodService extends android.app.Service implements android.view.KeyEvent.Callback {
     ctor public AbstractInputMethodService();
     method public android.view.KeyEvent.DispatcherState getKeyDispatcherState();
-    method public final boolean isUiContext();
     method public final android.os.IBinder onBind(android.content.Intent);
     method public abstract android.inputmethodservice.AbstractInputMethodService.AbstractInputMethodImpl onCreateInputMethodInterface();
     method public abstract android.inputmethodservice.AbstractInputMethodService.AbstractInputMethodSessionImpl onCreateInputMethodSessionInterface();

core/java/android/inputmethodservice/AbstractInputMethodService.java

@@ -300,13 +300,6 @@ public abstract class AbstractInputMethodService extends WindowProviderService
         return false;
     }
 
-    // TODO(b/149463653): remove it in T. We missed the API deadline in S.
-    /** @hide */
-    @Override
-    public final boolean isUiContext() {
-        return true;
-    }
-
     /** @hide */
     @Override
     public final int getWindowType() {