[applet/{analog,digital}-clock] Use `onPressed: wasExpanded = ...` idiom

This is a common snippet of code in applets. It prevents applet from
re-expanding again when user clicks on the compact representation when
the applet is already expanded and located on a desktop containment.

See also: 79bcefdd
FIXED-IN: 5.24.7 5.25.4 5.26

(cherry picked from commit 335ee5ba)