Revert "lru_cache preserves signature of wrapped function (#6221)"

[JukkaL]

This reverts commit 8bda66a.

The change causes issues with ParamSpec implementations in type
checkers, at least pyright and my work-in-progress support for
ParamSpec in mypy. It's not yet clear how to fix the issues, so I
think that it's best to revert this, at least temporarily until we've
found a good solution. See #6347 for context.

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

isort (https://github.com/pycqa/isort.git)
- isort/place.py:17: error: Returning Any from function declared to return "str"

pandas (https://github.com/pandas-dev/pandas.git)
- pandas/core/dtypes/cast.py:498: error: unused "type: ignore" comment

pydantic (https://github.com/samuelcolvin/pydantic.git)
- pydantic/tools.py:34: error: unused "type: ignore" comment

pytest (https://github.com/pytest-dev/pytest.git)
+ src/_pytest/config/__init__.py:1683: error: Argument 1 to "filterwarnings" has incompatible type "*Tuple[str, str, Type[Warning], str, int]"; expected "Union[Literal['default'], Literal['error'], Literal['ignore'], Literal['always'], Literal['module'], Literal['once']]"  [arg-type]
+ src/_pytest/config/__init__.py:1686: error: Argument 1 to "filterwarnings" has incompatible type "*Tuple[str, str, Type[Warning], str, int]"; expected "Union[Literal['default'], Literal['error'], Literal['ignore'], Literal['always'], Literal['module'], Literal['once']]"  [arg-type]
- src/_pytest/fixtures.py:1323: error: Unexpected keyword argument "params" for "FixtureFunctionMarker"  [call-arg]

aiohttp (https://github.com/aio-libs/aiohttp.git)
- aiohttp/multipart.py:518: error: Returning Any from function declared to return "str"  [no-any-return]
- aiohttp/multipart.py:692: error: Returning Any from function declared to return "str"  [no-any-return]
- aiohttp/connector.py:919: error: Returning Any from function declared to return "Optional[SSLContext]"  [no-any-return]
- aiohttp/connector.py:925: error: Returning Any from function declared to return "Optional[SSLContext]"  [no-any-return]
- aiohttp/connector.py:926: error: Returning Any from function declared to return "Optional[SSLContext]"  [no-any-return]
- aiohttp/client_reqrep.py:1010: error: Returning Any from function declared to return "str"  [no-any-return]

edgedb (https://github.com/edgedb/edgedb.git)
- edb/schema/objects.py:997: error: unused "type: ignore" comment
- edb/schema/objects.py:1992:9: error: Returning Any from function declared to return "QualName"
- edb/schema/objects.py:2223: error: unused "type: ignore" comment
- edb/schema/objects.py:2637:9: error: Returning Any from function declared to return "Name"
- edb/schema/schema.py:1146:9: error: Returning Any from function declared to return "FrozenSet[Cast]"
- edb/schema/schema.py:1156:9: error: Returning Any from function declared to return "FrozenSet[Cast]"
- edb/schema/schema.py:1166:9: error: Returning Any from function declared to return "FrozenSet[so.Object_T]"
- edb/schema/schema.py:1412:9: error: Returning Any from function declared to return "Optional[Migration]"
- edb/schema/scalars.py:132:9: error: Returning Any from function declared to return "bool"
- edb/schema/scalars.py:163:9: error: Returning Any from function declared to return "bool"
- edb/schema/scalars.py:176:9: error: Returning Any from function declared to return "int"
- edb/schema/casts.py:91:5: error: Returning Any from function declared to return "bool"
- edb/schema/casts.py:119:21: error: Returning Any from function declared to return "Optional[Type]"