Fix custom shortcut search not match

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/f8b1ba64a9ee45dcb2c36362858ecbec/

Change-Id: I630de129c008f147b19153cdca3bba25e6a8c03a
UserName length limit to 32 char

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/9b2cf489661f4b369c1a39d56ad5c5a4/#a5fa5e864bd24563943826a8a1e87633

Change-Id: Ib6a29cc0efa6b9e597f29092d81ce9850a282945