Remove now useless RTL code-comment on SwCommentRuler

RTL work was done by someone else.

Change-Id: I8b8b923ff3e336427a2dadeccab7c7176d51b2fe
Signed-off-by: Rodolfo Ribeiro Gomes <rodolforg@gmail.com>
Reviewed-on: https://gerrit.libreoffice.org/6716
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>