feat(MapView): remove redundant onMarkerPress interception

See react-native-maps#1741. I'm not really sure if it fixed
anything back then, or just helped making it easier to access the data
of the nativeEvent.

Either way, this will never be called today, as the consumer-provided
prop will override this, as the consumer props are spread AFTER
this is passed, as opposed to back when the fix was introduced.

src/MapView.tsx

@@ -171,7 +171,6 @@ class MapView extends React.Component<Props, State, SnapShot> {
     };
 
     this._onMapReady = this._onMapReady.bind(this);
-    this._onMarkerPress = this._onMarkerPress.bind(this);
     this._onChange = this._onChange.bind(this);
     this._onLayout = this._onLayout.bind(this);
   }
@@ -259,12 +258,6 @@ class MapView extends React.Component<Props, State, SnapShot> {
     }
   }
 
-  _onMarkerPress(event) {
-    if (this.props.onMarkerPress) {
-      this.props.onMarkerPress(event.nativeEvent);
-    }
-  }
-
   private _onChange({ nativeEvent }: ChangeEvent) {
     this.__lastRegion = nativeEvent.region;
     const isGesture = nativeEvent.isGesture;
@@ -587,7 +580,6 @@ class MapView extends React.Component<Props, State, SnapShot> {
       props = {
         region: null,
         initialRegion: null,
-        onMarkerPress: this._onMarkerPress,
         onChange: this._onChange,
         onMapReady: this._onMapReady,
         onLayout: this._onLayout,
@@ -606,7 +598,6 @@ class MapView extends React.Component<Props, State, SnapShot> {
         style: this.props.style,
         region: null,
         initialRegion: null,
-        onMarkerPress: this._onMarkerPress,
         onChange: this._onChange,
         onMapReady: this._onMapReady,
         onLayout: this._onLayout,