Move tools tests into a general.shard directory in preparation to changing how we shard tools tests (#36108)

These are essentially self-inflicted race conditions. Instead of timeouts we're going to try a more verbose logging mechanism that points out when things are taking a long time.

* Fix `flutter test`e xpression eval tests

We weren't passing `beforeStart` through so the breakpoints were never being set, which means the evaluations were happening while the code was running.

* Ensure we wait for breakpoints before trying to evaluate

* Add some basic tests for evaluating expressions in `flutter test`

* Review tweaks