Instead of the strict check-all-our-crates, generate a fake Cargo.lock
and add it to the report generated by check-all-our-lock-files.
check-all-our-crates was a reimplementation of cargo-audit anyways and
prevented us from updating the advisory db due to its strict
model (failing on any advisory).
Change-Id: I264a7f1a5058a527cbc46d26225352ecd437a22b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5230
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>