Doc build pipeline issue fix

[lanluo-nvidia]

Description

We now templaterized the toolchains/ci_workspaces/WORKSPACE.x86_64.release.rhel.tmpl file, it requires the following two envs:
CHANNEL/CU_VERSION

in both linux, windows build pipeline, those two are populated correctly, however in doc gen pipeline, thoese two are not set.

http_archive(
    name = "libtorch_pre_cxx11_abi",
    build_file = "@//third_party/libtorch:BUILD",
    strip_prefix = "libtorch",
    urls = ["https://download.pytorch.org/libtorch/${CHANNEL}/${CU_VERSION}/libtorch-shared-with-deps-latest.zip"],
)

Type of change

Please delete options that are not relevant and/or add your own.

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project (You can use the linters)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas and hacks
• I have made corresponding changes to the documentation
• I have added tests to verify my fix or my feature
• New and existing unit tests pass locally with my changes
• I have added the relevant labels to my PR in so that relevant reviewers are notified

[narendasan]

LGTM