fdo#72267 boolean_test is subsumed by general case "foo IS [NOT] bar"

Change-Id: Ie9666b1c8878dd26593629b4b64d74b7448f98c1
Reviewed-on: https://gerrit.libreoffice.org/6974
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>