[envpool] upgrade Bazel 8 toolchain and release build infra

[Trinkle23897]

Why/Context/Summary

• Upgrade the Bazel toolchain stack in WORKSPACE mode for Bazel 8.6.0: explicitly pin rules_cc 0.2.17, rules_java 9.6.1, protobuf 34.1, rules_foreign_cc 0.15.1, and raise rules_python to the highest working version on this stack (1.6.3).
• Fix Bazel 8 compatibility issues in the repo by replacing plain directory genrule outputs with declared-directory copies for Atari / MuJoCo / Procgen / ViZDoom assets, and keep the narrow pybind11_bazel / Boost compatibility patches needed by the current WORKSPACE build.
• Update the dev and release build surfaces to match the new support policy: dev Docker moves to CUDA 13.1.1 on Ubuntu 24.04, docker-dev-cn is dropped, and the release path is switched to manylinux_2_28_x86_64 with the workflow and auditwheel platform tag aligned to that target.

Test plan

• dev-0: USE_BAZEL_VERSION=8.6.0 bazelisk test //... --enable_workspace --noenable_bzlmod --distdir=/root/code/envpool-phase3-verify/.distdir --config=test --spawn_strategy=local --test_output=all --nocache_test_results
• local: make docstyle
• local: workflow YAML parse check for .github/workflows/release.yml
• local: make lint did not surface code issues before stopping on a local environment problem (clang-format missing from PATH / sudo install unavailable on this machine)