[INTERNAL] m.ComboBox: dead code elimination (force selection feature)

- remove functionality that was added for the force selection feature
(currently not implemented)

Change-Id: I9ffd09992d543604f22d56fafcf410eabefc974e
CR-Id: 012003146900009288732014
Merge "[INTERNAL] m.ComboBox: dead code elimination (force selection feature)" into rel-1.26