[FIX] sap.m.DateTimePicker: fix unit tests
[FIX] sap.m.DateTimePicker: fix unit tests

Change-Id: I4df0fdf91d74b967d8a829e8d9739eae67edfc58
BCP: 1780506472

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