refactor: erase configuration from interned storage

[MichaReiser]

Erases configuration from interned storage and cold paths to reduce downstream monomorphization while retaining specialized reuse checks on the successful-hit path.

Measured on ty:

• total LLVM lines fall from 3,284,622 to 3,096,046 (5.74%)
• intern-related LLVM lines from 276,433 to 216,077 (21.83%)
• DateType instructions from 674,414,109 to 673,205,080 (0.179%).
• The Salsa new[InternedInput] simulation improves from 598 to 597 instructions
• the debug ty binary falls by 3.38%
• the stripped release binary by 1.25%
• the maturin wheel by 0.84%.

[netlify]

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[codspeed-hq]

Merging this PR will not alter performance

✅ 11 untouched benchmarks
🗄️ 22 archived benchmarks run¹

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_{Comparing MichaReiser:erase-interned-configuration (132d710) with master (b826c8c)}

Footnotes

1. 22 benchmarks were run, but are now archived. If they were deleted in another branch, consider rebasing to remove them from the report. Instead if they were added back, click here to restore them. ↩

[MichaReiser]

Only change is that the code moved into this inner function