[TIMOB-23989] Android: When the back button is pressed on android it closes the app even if it is not the last window with SDK 6.0.0

This is a regression.

Steps to reproduce:

1. Use the code below in the app.js

var win = Ti.UI.createWindow();

win.addEventListener('click',function(){
    var win1 = Ti.UI.createWindow({
        backgroundColor:'teal'
    });
    
    win1.open();
});

win.open();

2. Click on the first window. 3. You should see the second window with the background color teal. 4. Press the android back button.

Actual results:

1. The app closes.

Expected results:

1. App should go back to the first window rather than closing.