fdo#75256 Improve sifr icontheme

Shrink and grow is the way to go...

Change-Id: Ie8dfc18ef6b0b9f712dfc6684d0e75eb3b04f0f0
Reviewed-on: https://gerrit.libreoffice.org/12505
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>