Add geth evm build to CI for tests_pytest_py*3 tox envs #2557
Description
Problem
The packages/testing unit test src/execution_testing/client_clis/tests/test_transition_tools_support.py::test_ci_multi_t8n_support checks that GethTransitionTool is available in CI. This requires the evm command (from go-ethereum/cmd/evm).
The tests_pytest_py3 and tests_pytest_pypy3 CI jobs do build geth, but the test passes regardless. This is because under tox, the CI environment variable was not in passenv for tests_pytest_py3. The running_in_ci fixture returned False, so the test never actually asserted that geth or evmone were available. The test was passing trivially.
Fix
Use build-evm-client/geth in both tests_pytest_py3 and tests_pytest_pypy3 jobs in .github/workflows/test.yaml. This builds the evm command from source and adds it to PATH. We should additionally cache the binary built as does .github/actions/build-evmone/action.yaml.
Imo, it's worth getting this in at some point because I've had fails locally due to geth being present locally, but these fails were not picked up in CI, cf #2014 (comment) (in which I also initially made a lazy attempt to download a more recent geth via ./scripts/download_geth_linux.py, but that didn't work out).