Improve Server Pro tests to use semantic selectors (#29790)

* Replace placeholders with labels

* Add 'Close dialog' label to modal close button to distinguish from footer Close button

* Add and translate heading on the not found page

* Update textarea to have id matching label's for attribute
Simplify test for template description textarea

* Label PDF zoom level dropdown button

* Improve test selectors to use semantic roles and accessible names

GitOrigin-RevId: d215ddca30ddf844cfffbcf0e528a601b134d772

services/web/test/frontend/features/settings/components/leave-section.test.tsx

@@ -35,7 +35,7 @@ describe('<LeaveSection />', function () {
     )
 
     const cancelButton = screen.getByRole('button', {
-      name: 'Close',
+      name: 'Cancel',
     })
 
     fireEvent.click(cancelButton)