evo2-sae: remove the dedicated CI lane (defer CI for now)

Remove .github/workflows/unit-tests-interpretability-recipes.yaml per review (recoverable from
history / 9bedf2b). Keep .ci_build.sh + .ci_test_env.sh + the tests — those are the build/run
machinery (used by the Dockerfile and manual runs), not the CI lane. How to build + run the tests
is documented in the PR description; CI should later fold into the repo-wide recipe lane rather
than a bespoke workflow.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Polina Binder <pbinder@nvidia.com>

Author: polinabinder1