Convert overlapping input consumer exception to warning

- Only SysUI uses this mechanism, and re-registering an input consumer
  with the same name should not result in a crash as we can just replace
  the consumer and log accordingly (cross-user input consumer
  registration is not affected)

Bug: 353903219
Test: Manual, force multiple registrations of the input consumer
Flag: EXEMPT bugfix
Change-Id: I747034f36595ba37c22f7a0cb46ad11238d41296