Make hmi-switch-graphical-applications more generic

After relaxing hmi-switch-graphical-applications to use any application
some instructions were not properly updated. Update the test case to
be coherent with the new approach.

Signed-off-by: Walter Lozano <walter.lozano@collabora.com>

test-cases/hmi-switch-graphical-applications.yaml

@@ -21,5 +21,5 @@ run:
  steps:
    - "Open a graphical application from the UI, for instance Fonts Application"
    - "Open any file"
-   - "Without exiting Fonts, starts a second graphical application like Weston Terminal"   
-   - "Exit the Weston Terminal application"
+   - "Without exiting the application, starts a second graphical application like Weston Terminal"
+   - "Exit the second application"