How to best cleanup simulators after test timeout?

We were running into an issue where non-reused simulators would end getting left over when hosted iOS unit tests timed out. We have a patch that combines the trap handler that cleans up `test_tmp_dir` with a call to `xcrun simctl delete` to clean up single-use simulators, but it doesn't seem like a particularly scalable solution.

It'd be nice to formalize calling into `clean_up_simulator_action_binary` when test timeouts happen and how that cleanup script could detect that the test timed out.

Start by reading the existing test_tmp_dir trap handler and clean_up_simulator_action_binary, then inspect how hosted iOS unit-test timeouts are handled. Compare the proposed xcrun simctl delete approach with the cleanup action entry point. Done means timed-out tests reliably trigger single-use simulator cleanup without leaving simulators behind.

Written by the indexing model from the issue text.