fix: persistent task concurrency check (#5806)
### Description
A minor error formatting change and `--concurrency` parsing logic change
in order for us to match Go behavior.
### Testing Instructions
Integration test passes:
```
[1 olszewski@chriss-mbp] /Users/olszewski/code/vercel/turborepo/turborepo-tests/integration $ EXPERIMENTAL_RUST_CODEPATH=true .cram_env/bin/prysk --shell=bash tests/persistent_dependencies/10-too-many.t
.
# Ran 1 tests, 0 skipped, 0 failed.
```
Closes TURBO-1268
Co-authored-by: Chris Olszewski <Chris Olszewski>
