[red-knot] mypy_primer: Use upstream repo (#17500)
## Summary
Switch to the official version of
[`mypy_primer`](https://github.com/hauntsaninja/mypy_primer), now that
Red Knot support has been upstreamed (see
https://github.com/hauntsaninja/mypy_primer/pull/138,
https://github.com/hauntsaninja/mypy_primer/pull/135,
https://github.com/hauntsaninja/mypy_primer/pull/151,
https://github.com/hauntsaninja/mypy_primer/pull/155).
## Test Plan
Locally and in CI
