Set Max User Name 32

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/9b2cf489661f4b369c1a39d56ad5c5a4/#336d791c47b04f88a4f968d9b8d882a0

Change-Id: I52393ca96b51b5992aae70c3966cbbd019d7b983