fix: remove references to fully rolled out zisi_fix_symlinks feature flag

[mrstork]

Summary

Removes references to a fully rolled out feature flag
https://app.devcycle.com/o/org_dhCAK5hN1u5tXdf9/p/shared/features/65b78c6542b02ea65e48a3ea

Part of FRB-1560

---

For us to review and ship your PR efficiently, please perform the following steps:

• Open a bug/issue before writing your code 🧑‍💻. This ensures
  we can discuss the changes and get feedback from everyone that should be involved. If you`re fixing a typo or
  something that`s on fire 🔥 (e.g. incident related), you can skip this step.
• Read the contribution guidelines 📖. This ensures
  your code follows our style guide and passes our tests.
• Update or add tests (if any source code was changed or added) 🧪
• Update or add documentation (if features were changed or added) 📝
• Make sure the status checks below are successful ✅

A picture of a cute animal (not mandatory, but encouraged)

[orinokai]

Simples 😁