[FIX] sap.m.MultiCombobox: Input value kept, on de-select of list item
- Removed that logic which fills the value on List item "focus" 
- cherry pick from Master

Change-Id: Ia828b36843b7a70e29b3ede76f6baae719bb42a7
BCP: 1482013158
CR-Id: 012003146900009267962014
Merge "[FIX] sap.m.MultiCombobox: Input value kept, on de-select of list item - Removed that logic which fills the value on List item "focus"  - cherry pick from Master" into rel-1.26