fdo#75924 update button labels of spellcheck dialog

Change-Id: I1009c08fbf32a49a54bea97551883dd140fc1515
Reviewed-on: https://gerrit.libreoffice.org/8522
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>