[INTERNAL] ListBase: unbindAggregation now do not empty aggregations
[INTERNAL] ListBase: unbindAggregation now do not empty aggregations

This reverts commit de1a70979cbd504dda831f52104823b98e600e17.

Change-Id: Icd860cd79a0de7ddd3696d7138a2ac38f1a6424a

SAP/openui5,SAP/openui5,SAP/openui5,SAP/openui5