Make team planner tests slightly faster

- `search_user_to_add` call is useless as the `select_user_to_add`
  already does a search before the selection.

- `click_add_user` does not need to wait when checking the input
  presence. As it is almost always absent, this save 5 seconds.

modules/team_planner/spec/support/pages/team_planner.rb

@@ -227,14 +227,14 @@ def click_on_submit
     def add_assignee(name)
       click_add_user
       page.find('[data-qa-selector="tp-add-assignee"] input')
-      search_user_to_add name
       select_user_to_add name
     end
 
     def click_add_user
-      # Close the existing, if it is open
-      is_open = page.all('[data-qa-selector="tp-add-assignee"] input').first
-      page.find('[data-qa-selector="tp-assignee-add-button"]').click unless is_open
+      is_open = page.has_selector?('[data-qa-selector="tp-add-assignee"] input', wait: 0)
+      return if is_open
+
+      page.find('[data-qa-selector="tp-assignee-add-button"]').click
     end
 
     def select_user_to_add(name)