IndexSlice typing is no longer correct

[Dr-Irv]

Describe the bug
Prior to #282, pd.IndexSlice returned a tuple with specific types. That is no longer the case.

To Reproduce

import pandas as pd

df = (
    pd.DataFrame({"x": [1, 2, 2, 3, 4], "y": [10, 20, 30, 40, 10]})
    .assign(z=lambda df: df.x * df.y)
    .set_index(["x", "y"])
)
ind = pd.Index([2, 3])
reveal_type(pd.IndexSlice[ind, :])

With pandas-stubs 1.4.4.220911, we get:

pyright reports:

isli.py:4:13 - information: Type of "pd.IndexSlice[ind, :]" is "tuple[Unknown, ...]"

mypy reports:

isli.py:4: note: Revealed type is "builtins.tuple[Any, ...]"

With pandas-stubs 1.4.4.220906, we get:

pyright:

isli.py:9:13 - information: Type of "pd.IndexSlice[ind, :]" is "tuple[str | str_ | bytes | date | datetime | timedelta | bool | complex | Timestamp | Timedelta | slice, ...]"

mypy:

isli.py:9: note: Revealed type is "builtins.tuple[Union[Union[builtins.str, numpy.str_], Union[builtins.str, builtins.bytes, datetime.date, datetime.datetime, datetime.timedelta, builtins.bool, builtins.complex, pandas._libs.tslibs.timestamps.Timestamp, pandas._libs.tslibs.timedeltas.Timedelta], builtins.slice], ...]"

Please complete the following information:

• OS: Windows 10
• python version: 3.10
• mypy 0.971, pyright 1.269
• version of installed pandas-stubs: 1.4.4.220911

Additional context

@bashtage needs to look at this, because change in #282 is what messed this up.