[DocsUI]: Fix testSearchView_ShouldHideOptionMenuOnExpanding

This CL make official the current behavior. See the bug for more
details. Short story, it seems that this test was never properly run on
720 or wider displayes. When we have a wide display the UI is not using
the full bar for the search view.

Bug: 431139840
Test: atest DocumentsUIGoogleTests
Flag: com.android.documentsui.flags.use_material3
Change-Id: I705bc15fc1d369eea5a9b140381276d60b348896