Rollup merge of #142231 - Kobzol:master-cache-ci, r=marcoieni

Run `calculate_matrix` job on `master` to cache citool builds

As discussed in https://rust-lang.zulipchat.com/#narrow/channel/242791-t-infra/topic/PR.20ci.20seems.20much.20to.20slow/with/523028903, the current `rust-cache` solution for `citool` doesn't work, because we don't ever write to the cache from `master`, so the cache is empty on PR CI jobs.

This PR runs the `calculate_matrix` job on `master`, with the only motivation to actually prime the cache.

r? `@marcoieni`

Author: matthiaskrgr