StepPlayer.cleanUp() doesn't close all dialogs.

## Context
When more than one dialog were opened and a failure happened, only one dialog was closed by StepPlayer.cleanUp(). It lead to other failures of the following release tests.

## Description
The `cleanUp` method is now calling `WindowMonitor.getWindows()` instead of `TestHelper.getWindow(dialogFinder)` to find all opened windows and close them.