Using core_schema.InvalidSchema instead of metadata injection + checks

[sydney-runkle]

Making progress on #10299
Requires pydantic/pydantic-core#1469

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[codspeed-hq]

CodSpeed Performance Report

Merging #10523 will not alter performance

_{Comparing invalid-schema (2e2c059) with main (ba50d94)}

Summary

✅ 44 untouched benchmarks

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[sydney-runkle]

A bit stumped here. @davidhewitt, maybe we could chat on Monday. Do you think it makes sense to have InvalidSchema as a member of the CoreSchema type alias? It doesn't have a serialization key, which is throwing off the type checker in cases where we apply schema['serialization'] to a CoreSchema instance...

Going to pause dev here until we've made a decision on that front.