Fixes test that is currently failing

Refactors yesterday caused tests to fail because of dependencies getting
initialized earlier. Refactored so that they are initialized late enough
for the tests to be able to mock them correctly.

Also fixes bug where handles would still show when there was no
Assistant.

Test: atest AssistHandleBehaviorControllerTest
BUG:132424950
Fixes: 134086503
Change-Id: I645a2529bf56b5e996e8250267ead87bed9f4f2b
FIX:132424950