XRefreshable::testRefreshListener() fails on read-only filesystem
because the ScDDELinksObj.ods cannot be loaded read-write.

It is loaded read-write since commit
5b2794e2.

Change-Id: I27b954b216acd3d138ade0d3f1b21fedd2f74fb1
Reviewed-on: https://gerrit.libreoffice.org/67071
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>