fdo#73414 Remove Increase Font limits for Writer

and re-use the same code in sidebar.

Change-Id: Ic342be479f6f5b23ea2dd79b7cf6c77897b27dc1
Reviewed-on: https://gerrit.libreoffice.org/7398
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>