Bug 15348: (follow-up) Fix filtering results on estimated delivery date

Bug 15348: (follow-up) Fix filtering results on estimated delivery date

Adding another clause to the SQL so that the specified estimated
delivery date is used for filtering first, and the calculated delivery
date is used if there is no specified estimated delivery date.

Signed-off-by: Christian Stelzenmüller <christian.stelzenmueller@bsz-bw.de>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>