Simplify IInputMethodInvoker#updateEditorToolType() a bit

This is a mechanical refactoring CL that simplifies

  IInputMethodInvoker#updateEditorToolType(),

which was added recently [1], by making its return value void from
boolean, because no one checks its return value.

There should be no observable behavior change.

 [1]: I91ea9204ef62697b8942b0f350169382f18b3278
      e5f49917

Bug: 234882948
Test: presubmit
Change-Id: Id9b14d8ced97b6a57f1cc5539f4f392aa70f9e51