Create XL E2E CI job

[nathan-weinberg]

Similar to what we have in the Core repo

[nathan-weinberg]

cc @courtneypacheco

[nathan-weinberg]

@instructlab/training-maintainers can one of you assign this issue to Courtney?

[courtneypacheco]

fyi: This feature can be added once #396 is fixed.

The XL e2e job currently runs into the same bug as the large e2e job does.

[JamesKunstle]

@courtneypacheco @nathan-weinberg
I think the future of this job's role will be a benchmarking or convergence test rather than being similar to our other e2e jobs. We may want to repurpose this issue for that work.