Remove old hermes nightly script files (#56752)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/56752

Delete the old script files that were renamed in prior commits:
- scripts/releases/use-hermes-nightly.js (renamed to use-hermes-prebuilt.js)
- scripts/try-set-nightly-hermes-compiler.js (renamed to try-set-hermes-compiler-prebuilt.js)

These deletions were accidentally omitted from their respective rename commits.

## Changelog:
[Internal] -

Reviewed By: cortinico

Differential Revision: D104650744

fbshipit-source-id: a0f1e3279622f792a0e79d011d942539e5168eaf