Remove @UnsupportedAppUsage from IInputConnectionWrapper#mInputConnection

As already mentioned in Bug 115609023 and confirmed in Bug 194297014,
we are mostly confident that this @UnsupportedAppUsage was a false
positive.

Bug: 115609023
Fix: 194297014
Test: presubmit
Change-Id: Ie70099c2f5f926ce64324998a61eb54649e553f9

core/java/com/android/internal/view/IInputConnectionWrapper.java

@@ -89,7 +89,6 @@ public final class IInputConnectionWrapper extends IInputContext.Stub {
 
     @GuardedBy("mLock")
     @Nullable
-    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
     private InputConnection mInputConnection;
 
     private Looper mMainLooper;