Wait for scan completion in max cameras test

Improve stability of test_max_cameras_prevented by waiting for the scan to finish before injecting results. Removed the backend='fake' remark from the docstring and added qtbot.waitUntil(lambda: not d._is_scan_running(), timeout=1000) and d._on_scan_finished() around the simulated scan result to ensure the dialog is in a stable state before interacting with UI widgets.

Author: C-Achard

tests/gui/camera_config/test_cam_dialog_e2e.py

@@ -329,7 +329,7 @@ def _warn(parent, title, text, *args, **kwargs):
 @pytest.mark.gui
 def test_max_cameras_prevented(qtbot, monkeypatch, patch_detect_cameras):
     """
-    Dialog enforces MAX_CAMERAS enabled cameras. Use backend='fake' for stability.
+    Dialog enforces MAX_CAMERAS enabled cameras.
     """
     calls = {"n": 0}
 
@@ -357,7 +357,9 @@ def _warn(parent, title, text, *args, **kwargs):
 
         initial_count = d.active_cameras_list.count()
 
+        qtbot.waitUntil(lambda: not d._is_scan_running(), timeout=1000)
         d._on_scan_result([DetectedCamera(index=4, label="Extra")])
+        d._on_scan_finished()
         d.available_cameras_list.setCurrentRow(0)
 
         qtbot.mouseClick(d.add_camera_btn, Qt.LeftButton)