animation: Prevent spinner animation from resetting

animation: Prevent spinner animation from resetting

Currently, the search status spinner animation restarts on every
single keystroke while a search is in progress. This occurs because
redundant calls to `play()` replace the previous content and restart
the animation from the beginning.

This commit fixes this by ignoring redundant `play()` and `stop()` calls.

Closes https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/8695

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/4191>