DEV: Remove the use of Capybara::Session#quit (#24978)

Why this change?

This is what `Capybara::Session#quit` does:

```
    def quit
      @driver.quit if @driver.respond_to? :quit
      @document = @driver = nil
      @touched = false
      @server&.reset_error!
    end
```

One notable thing is that it resets server errors which means that any
server errors encountered by a session is cleared. That is not what we
want since it hides errors even though `Capybara.raise_server_errors`
has been set to `true`.

plugins/chat/spec/system/user_menu_notifications/sidebar_spec.rb

@@ -213,14 +213,13 @@ RSpec.describe "User menu notifications | sidebar", type: :system do
       channel.send_message("this is fine @#{other_user.username}")
       find(".invite-link", wait: 5).click
 
-      using_session(:user_1) do |session|
+      using_session(:user_1) do
         sign_in(other_user)
         visit("/")
         find(".header-dropdown-toggle.current-user").click
 
         expect(find("#user-menu-button-chat-notifications")).to have_content(1)
         expect(find("#quick-access-all-notifications")).to have_css(".chat-invitation.unread")
-        session.quit
       end
     end
   end