Ensure @Before and @Test run on the same thread in AndroidJUnit4ClassRunner.

[copybara-service]

Ensure @before and @test run on the same thread in AndroidJUnit4ClassRunner.

Currently, AndroidJUnit4ClassRunner inherits standard JUnit 4 behavior where
timeouts are applied only to the test method itself. If a test timeout is
set (e.g., passed by TradeFed or runner arguments), FailOnTimeout executes
the test method in a separate thread.

Since setup (@before) and teardown (@after) are applied outside this
timeout, they run on the caller thread, causing a thread mismatch. This
prevents ThreadLocal variables initialized in setup from being accessible in
the test.

This CL modifies AndroidJUnit4ClassRunner to apply the timeout to the
combined statement of setup, test, and teardown. This is achieved by:

1. Overriding withAfters to wrap the combined statement in FailOnTimeout.
2. Overriding withPotentialTimeout to be a no-op, preventing double
   timeout application.

This ensures all lifecycle methods run on the same thread spawned by the
timeout.

NOTE: Because the timeout now wraps setup and teardown, any time spent in
@before or @after will now count towards the test timeout.