test: `tests/lake/run_test.sh` (#13501)

This PR removes the Makefile-based Lake test runner and replaces it with
`run_test.sh` and `run_clean.sh`. These are still not designed for use
with the `with_*.sh` runners, but this a step closer to that
eventuality.

It also adds a line to `CLAUDE.md` informing Claude how to build and run
a single Lake test.
7 files changed