Fix texture upload callbacks in Java/Kotlin (#6939)

* Fix texture upload callbacks in Java/Kotlin

* Update release notes

android/filament-android/src/main/cpp/Texture.cpp

@@ -511,9 +511,7 @@ public:
 
 private:
     void* mData = nullptr;
-    jobject mBitmap = nullptr;
-    jobject mHandler = nullptr;
-    jobject mCallback = nullptr;
+    jobject mBitmap{};
     AndroidBitmapInfo mInfo{};
 };