[ty] remove the visitor parameter in the recursive_type_normalized_impl method

[mtshiba]

Summary

This is a follow-up to #20566.

I revisited the recursive_type_normalized_impl method and realized that the visitor parameter is no longer necessary (the method doesn't expand type aliases, so there's no risk of infinite recursion), so I removed it.
I also added some more comments to some parts.

Test Plan

N/A

[astral-sh-bot]

Diagnostic diff on typing conformance tests

No changes detected when running ty on typing conformance tests ✅

[astral-sh-bot]

mypy_primer results

Changes were detected when running on open source projects

scikit-build-core (https://github.com/scikit-build/scikit-build-core)
+ src/scikit_build_core/_logging.py:153:13: warning[unsupported-base] Unsupported class base with type `<class 'Mapping[str, Style]'> | <class 'Mapping[str, Divergent]'>`
- Found 41 diagnostics
+ Found 42 diagnostics

No memory usage changes detected ✅