gs-details-page: Drop extra padding below addons section

It looks like it was accidentally left there after reorganising the UI.
It doesn’t look right.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Fixes: #1368
3 jobs for 1368-addons-padding in 5 minutes and 13 seconds (queued for 2 seconds)