Make "ime reset --user <userId>" consistent among users

With this CL

  adb shell ime reset --user <userId>

starts behaving in the same manner across users, meaning that there is
no special behavior when the userId is not IMMS#mCurrentUserId.

We expect no abrupt behavior change in this CL.

Bug: 350386877
Bug: 350834650
Test: manually verified
Flag: EXEMPT refactor
Change-Id: I4c776b45bb7d96d8f7dd49c71e269ffa310389c6