Followup to 58f121ef;
OConnection must not be held by rtl::Reference as that creates a cycle.

(regression from 497e40ad)

Change-Id: Ibd56d335e3e2631c5a57ea435f1035e89868a5a6
Reviewed-on: https://gerrit.libreoffice.org/73155
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>