Fixes https://github.com/pydantic/pydantic/issues/7611

Long term I think a plan to allow pydantic-core to minimize the validation runtime cost of using referenced schemas (https://github.com/pydantic/pydantic-core/pull/989) makes the most sense, but this will do for now. We may even be able to add back some of the caching, but will have to be smarter about it.

This degrades the performance of [this schema building benchmark](https://github.com/pydantic/pydantic/blob/main/tests/benchmarks/test_fastapi_startup_generics.py) from `2.5s` to `3s` on my laptop.

Selected Reviewer: @dmontagu
Remove schema building caches. Fixes https://github.com/pydantic/pydantic/issues/7611

Long term I think a plan to allow pydantic-core to minimize the validation runtime cost of using referenced schemas (https://github.com/pydantic/pydantic-core/pull/989) makes the most sense, but this will do for now. We may even be able to add back some of the caching, but will have to be smarter about it.

This degrades the performance of [this schema building benchmark](https://github.com/pydantic/pydantic/blob/main/tests/benchmarks/test_fastapi_startup_generics.py) from `2.5s` to `3s` on my laptop.

Selected Reviewer: @dmontagu
"""
Test mypy failure with invalid types.
"""
from datetime import datetime
from typing import List, Optional

from pydantic import BaseModel


class Model(BaseModel):
    age: int
    first_name = 'John'
    last_name: Optional[str] = None
    signup_ts: Optional[datetime] = None
    list_of_ints: List[int]


m = Model(age=42, list_of_ints=[1, '2', b'3'])

print(m.foobar)
# MYPY: error: "Model" has no attribute "foobar"  [attr-defined]

"""
Test mypy failure with invalid types.
"""
from datetime import datetime
from typing import List, Optional

from pydantic import BaseModel


class Model(BaseModel):
    age: int
    first_name = 'John'
    last_name: Optional[str] = None
    signup_ts: Optional[datetime] = None
    list_of_ints: List[int]


m = Model(age=42, list_of_ints=[1, '2', b'3'])

print(m.foobar)
# MYPY: error: "Model" has no attribute "foobar"  [attr-defined]
