[ROCm] continuous: build jax/jaxlib on fork runners
The nightly flow already builds the base jax/jaxlib wheels on the fork's
own runners (see "[ROCm] nightly: build jax/jaxlib on fork runners"),
because upstream stopped reliably publishing them to
gs://jax-nightly-artifacts/latest. The continuous flow was left behind:
build-jax-artifact and build-jaxlib-artifact are gated on the jax-ml
owner, so on the fork the ROCm legs silently fell back to that same
stale GCS bucket.
Apply the nightly pattern to the continuous flow so both consume freshly
built wheels. Upstream (jax-ml) behavior is unchanged.
- wheel_tests_continuous.yml: new fork-only build-rocm-jax-jaxlib job
uploading to the same wheel-tests-continuous S3 prefix as the ROCm
plugin/pjrt wheels; wired into the needs of both ROCm test legs, which
now pass jax-jaxlib-source=s3 on the fork.
- select_continuous_wheel_test_jobs.py: register build_rocm_jax_jaxlib as
a build job required by run_pytest_rocm and run_bazel_test_rocm, and
exclude it from per-job connection halts like the other ROCm jobs.
Only Python 3.12 is built, matching the Python versions the continuous
ROCm test legs actually consume; unlike plugin/pjrt these wheels are not
published, so building 3.13/3.14 every three hours would be wasted work.
