Use GitHub mirrors of mlplatform submodules to unbreak ExecuTorch CI

[swolchok]

Stack from ghstack (oldest at bottom):

• -> #6989

CI jobs have been failing due to availability issues with these submodules. mirrors should unbreak CI.

Differential Revision: D66255556

[pytorch-bot[bot]]

:link: Helpful Links

:test_tube: See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/6989

• :page_facing_up: Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

:heavy_exclamation_mark: 1 Active SEVs

There are 1 currently active SEVs. If your PR is affected, please view them below:

• [DomainsOnly] Jobs fail with GLIBC version not found

:x: 1 New Failure

As of commit 4b61b9372a61ed7af9a00b4fcfad196e7192cfba with merge base dcacde01d355b5f5082301edcdc9774dd3392f36 ():

NEW FAILURE - The following job has failed:

* [Lint / lintrunner / linux-job](https://hud.pytorch.org/pr/pytorch/executorch/6989#33286107153) ([gh](https://github.com/pytorch/executorch/actions/runs/11941386930/job/33286107153)) `>>> Lint for backends/qualcomm/quantizer/custom_annotation.py:`

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[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D66255556

[mcr229]

how doees mirror work? is it managed by the original gitlab owners?

[swolchok]

how doees mirror work? is it managed by the original gitlab owners?

• gitlab is not involved here at all
• we'll need to push to it manually, but we already pin submodule commits

[swolchok]

merging now because the "checkout repo" step in CI has clearly succeeded and that's what changed. lintrunner issue is already fixed on main

[digantdesai]

@robell