Auto merge of #22117 - asajeffrey:magicleap-ci, r=jdm

Add magicleap builder

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Add a magicleap builder to `etc/ci/buildbot_steps.yml` to gate releases on building the magicleap library. This doesn't yet check for building the magicleap app, or add a nightly release. That'll be a later PR.

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes do not require tests because it's adding a build test

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