Aqbanking online transfer: Disable SEPA direct debit menu item again because no bank supports it.

The (SEPA) banks apparently only support multi-jobs, not single jobs, but the
former is not yet in aqbanking and not yet in gnucash.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@22811 57a11ea4-9604-0410-9ed3-97b8803252fd