Detangle shared AndroidTest.xml for hwui_unit_tests/hwuimicro/hwuimacro

This change prevents multiple binaries from being pushed / executed when
only one of them was requested, which is currently causing `atest
hwui_unit_tests` to fail if hwuimacro or hwuimicro weren't manually
built first.

AFAICT, other projects don't tend to share AndroidTest.xml files for
multiple binaries.

Could this break something? Who knows. :) However, various tools seem to
get confused with the current ambiguity, and seem to often run multiple
binaries when only one of them was requested, or just break entirely. My
belief / hope is that anything expecting e.g. hwuimicro to run will
actually be running e.g. `atest hwuimicro` instead of running e.g.
`atest hwui_unit_tests` and expecting hwuimicro to also run as a side
effect.

Test: atest hwui_unit_tests, atest hwuimicro, atest hwuimacro
Bug: b/338077634
Flag: TEST_ONLY
Change-Id: I0b3f1b82abec09a6444293023901c1f4887270eb