Defer (more) complex object creation until used.

As part of supporting SysUI multivalentTests under the new Ravenwood
testing environment, tests need to be more careful about only
creating and interacting with "complex" objects when they're actually
needed by a test.  Attempting interactions during <init> or <clinit>
of the overall test class fails on Ravenwood when these complex
objects aren't yet supported, and they throw an exception.

This change is a continuation of the recent `by lazy` work, expanded
to catch examples that have emerged over the recent few weeks.  There
are also a few tests where `by lazy` left some dirty state between
test cases, so we pivot those tests to use `lateinit` instead so
that all existing tests remain passing.

Bug: 319647875
Test: atest SystemUiRoboTests
Change-Id: I2a646ad8d189fd9545123e9585796f35b4290b12