Remove: Unnecessary Example App code (because #56 issue resolved)

Author: note11g

example/android/app/src/main/kotlin/dev/note11/flutter_naver_map/flutter_naver_map_example/MainActivity.kt

@@ -3,9 +3,4 @@ package dev.note11.flutter_naver_map.flutter_naver_map_example
 import android.os.Bundle
 import io.flutter.embedding.android.FlutterActivity
 
-class MainActivity : FlutterActivity() {
-    override fun onCreate(savedInstanceState: Bundle?) {
-        intent.putExtra("background_mode", "transparent")
-        super.onCreate(savedInstanceState)
-    }
-}
+class MainActivity : FlutterActivity() {}