chore: skip building turborepo for rust tests (#6165)
### Description
I noticed we were waiting on on a full `turborepo` build before starting
the Rust unit tests. By skipping this we can get to Rust test failures a
lot faster. I'm *almost* 100% positive none of our unit tests require
this binary to be present, but we should verify that CI passes.
### Testing Instructions
CI Rust tests pass without waiting for a turborepo build
Closes TURBO-1458
Co-authored-by: Chris Olszewski <Chris Olszewski>
