Inconsistent behavior between slice() as an expression on a column and slice() on a Series/DataFrame

[JSteilberg]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

>>> pl.DataFrame({"a": [1,2,3,4,5]}).select(pl.col("a").slice(-6))
shape: (5, 1)
┌─────┐
│ a   │
│ --- │
│ i64 │
╞═════╡
│ 1   │
│ 2   │
│ 3   │
│ 4   │
│ 5   │
└─────┘
>>> pl.DataFrame({"a": [1,2,3,4,5]}).slice(-6)
shape: (4, 1)
┌─────┐
│ a   │
│ --- │
│ i64 │
╞═════╡
│ 1   │
│ 2   │
│ 3   │
│ 4   │
└─────┘
>>> pl.Series([1,2,3,4,5]).slice(-6)
shape: (4,)
Series: '' [i64]
[
	1
	2
	3
	4
]

I would highly prefer the first behavior, as it is what Python does for negative index out-of-bounds:

>>> [1,2,3,4,5][-6:]
[1, 2, 3, 4, 5]

Log output

No response

Issue description

Often there is a need to support capping a list to some maximum length. I know there are other ways to achieve what I want, but it seems like the above behavior should be consistent as the docs do not specify any functional difference between slicing on a DataFrame/Series/Expr.

Expected behavior

I would expect all three examples to return [1,2,3,4,5] (in the applicable datastructure), as slicing beyond the beginning of the list in Python tends to clamp to the beginning rather than loop back around to the end.

Installed versions

--------Version info---------
Polars:              1.6.0
Index type:          UInt64
Platform:            Linux-6.8.0-40-generic-x86_64-with-glibc2.35
Python:              3.12.2 | packaged by conda-forge | (main, Feb 16 2024, 20:50:58) [GCC 12.3.0]

----Optional dependencies----
adbc_driver_manager  <not installed>
altair               <not installed>
cloudpickle          <not installed>
connectorx           <not installed>
deltalake            <not installed>
fastexcel            <not installed>
fsspec               2024.6.1
gevent               <not installed>
great_tables         <not installed>
matplotlib           3.8.4
nest_asyncio         <not installed>
numpy                1.26.4
openpyxl             <not installed>
pandas               2.2.2
pyarrow              16.1.0
pydantic             <not installed>
pyiceberg            <not installed>
sqlalchemy           <not installed>
torch                <not installed>
xlsx2csv             <not installed>
xlsxwriter           <not installed>

[lmocsi]

And the expressions pl.DataFrame({"a": [1,2,3,4,5]}).slice(-10) and pl.Series([1,2,3,4,5]).slice(-10) return an empty df / series.
(with slice(-9) they return only the first value: 1)