MDL-77219 behat: Fix issue with headless

Although the error in the "I check that I can import recordings into
the Recording activity and then if I delete them" scenario is unrelated
to this patch, this commit needs to be applied too, in order to avoid
behat failures (because the "Import recording links" button is in the
edge of the window).

This is a backport of MDL-74272.

mod/bigbluebuttonbn/tests/behat/recordings_import.feature

@@ -57,6 +57,7 @@ Feature: Manage and list recordings
   Scenario: I check that I can import recordings into the Recording activity and then if I delete them
   they are back into the pool to be imported again
     When I am on the "RoomRecordings1" "bigbluebuttonbn activity" page logged in as "admin"
+    And I change window size to "large"
     And I click on "Import recording links" "button"
     And I select "Test Course 1 (C1)" from the "sourcecourseid" singleselect
     And I select "RoomRecordings" from the "sourcebn" singleselect