Remove all `CARGO_*` env vars in tests
Usage of `CARGO_PROFILE_*` is generating unexpected warnings in tests in
rust-lang/rust#64316 so let's just blanket remove every env var that has
a `CARGO_*` prefix which generally means Cargo-specific env vars. Tests
practically all assume that they have blank configs right now.
Usage of `CARGO_PROFILE_*` is generating unexpected warnings in tests in
rust-lang/rust#64316 so let's just blanket remove every env var that has
a `CARGO_*` prefix which generally means Cargo-specific env vars. Tests
practically all assume that they have blank configs right now.
Only run these tests on one CI builder (not all platforms) though. This
is extremely resource intensive since it rebuilds libstd. Currently this
does not share a build directly like before because the number of tests
are supposed to be small, but if necessary we can add that in later too.
