CI is breaking on archaic downloads

[sauclovian-g]

The "Test s2n proofs" jobs in the CI for awslc and blst (but not apparently others) are failing because they're trying to download (and then not use, we think/hope) some ancient build results that just got purged from the saw website.

They need to be made to not do that.

[sauclovian-g]

This has been bodged so it doesn't fail by putting the ancient build results back; an actual fix is needed.

[RyanGlScott]

Now that I look more closely at this, I think that there is actually a relatively straightforward workaround available. This is because the awslc Dockerfile doesn't clone the upstream version of aws-lc-verification, but rather our own fork of it:

saw-script/s2nTests/docker/awslc.dockerfile

Lines 10 to 13 in 4658e03

	RUN mkdir -p /saw-script && \
	git clone https://github.com/GaloisInc/aws-lc-verification.git && \
	cd aws-lc-verification && \
	git checkout 9e9dde6882ade1f5d01c6d088e6dcca181358a74 && \

That commit is on this branch. As such, we could push a commit to this branch that removes the use of the nightly SAW download (here).

We can do something similar for blst job given that we own the https://github.com/GaloisInc/BLST-Verification repo. All we'd have to do is make sure that we don't download a nightly versions of things (see the code here).