fix(pagination): drop @overload stubs to resolve D105/D418 pydocstyle conflict

pydocstyle D105 requires docstrings on magic methods but D418 prohibits
docstrings on @overload stubs — these rules are irreconcilable for
@overload-decorated __getitem__. Since PaginationList is the only file in
the project using @overload, there is no established project pattern.

Drop the two stubs and keep only the concrete implementation with its
existing docstring. The union signature 'SupportsIndex | slice -> T | list[T]'
is correct; callers lose the narrowed return type but the runtime behaviour
is unchanged. Also removes the now-unused 'overload' import.

Author: stark256-spec

pyiceberg/utils/pagination.py

@@ -20,7 +20,7 @@
 from __future__ import annotations
 
 from collections.abc import Callable, Iterator
-from typing import SupportsIndex, TypeVar, overload
+from typing import SupportsIndex, TypeVar
 
 T = TypeVar("T")
 
@@ -116,12 +116,6 @@ def __ne__(self, other: object) -> bool:
     # Index / slice access
     # ------------------------------------------------------------------
 
-    @overload
-    def __getitem__(self, idx: SupportsIndex) -> T: ...  # noqa: D105
-
-    @overload
-    def __getitem__(self, idx: slice) -> list[T]: ...  # noqa: D105
-
     def __getitem__(self, idx: SupportsIndex | slice) -> T | list[T]:
         """Fetch pages as needed before returning the requested item(s)."""
         if isinstance(idx, slice):