Transition OSS Python dependencies and CI builds to hermetic Python.

[copybara-service]

Transition OSS Python dependencies and CI builds to hermetic Python.

Open-source builds and CI pipelines previously relied on legacy @pypi_<pkg>//:pkg repository targets, @release_or_nightly workspace rules, and host-installed Python packages (pip install) before invoking Bazel. With the migration to rules_python hermetic Python toolchains, Bazel resolves Python interpreter versions and wheel dependencies directly via requirements.txt lockfiles and @pypi//<pkg>:pkg targets, making host-level package installation and legacy workspace dependencies redundant and error-prone.

Migrate OSS Python dependency rewrites and oss_scripts/pip_package/BUILD targets to @pypi//<pkg>:pkg, remove the obsolete extra_py_deps helper and @org_tensorflow_datasets workspace archive, and declare explicit test dependencies in BUILD targets. Update oss_scripts/configure.sh and py_deps_profile.bzl to persist HERMETIC_PYTHON_VERSION, IS_NIGHTLY, and TF_VERSION into .bazelrc, re-evaluate the repository rule when environment variables change, and pin tensorflow==<TF_VERSION> (including --pre support for release candidates) when re-locking requirements, while simplifying presubmit, release, and Docker scripts to pass HERMETIC_PYTHON_VERSION instead of managing host virtual environments. Additionally, tag benchmark targets with benchmark-test and filter them out during bazel test so Python 3.12+ test runners do not fail on empty TestCase suites, ensure rules_ml_toolchain overrides tf_workspace0() in the same WORKSPACE evaluation chunk, and read only the first line of .bazelversion in run_tests.sh.