move heap dump from activity to test

move burden of taking heap dump from activity to the test runner.

keeping thread.sleep()s for now, but as a next step there should be a better way to time when to run pidof, and read the heap dump.

Test: working locally and now works on ABTD
Flag: TEST_ONLY
Bug: 444249947
Change-Id: Id03265b84169af447dc44af5295a82617da53b85

Change-Id: Ifea6230f718c4284ed691925f33deabae1cdf73e