BUG: fix empty suffix and prefix handling in pyarrow string methods

Python's `str.removeprefix("")` and `str.removesuffix("")` return the
original string.

The current pyarrow-backed implementation slices with `stop=0` or
`start=0` when the prefix or suffix is empty, which can result in
unexpected behavior instead of preserving the original values.

This PR adds explicit guards for empty prefix and suffix inputs and
includes tests to ensure parity with Python semantics.

Author: vkverma9534

pandas/core/arrays/_arrow_string_mixins.py

@@ -209,11 +209,14 @@ def _str_removeprefix(self, prefix: str):
         return self._from_pyarrow_array(result)
 
     def _str_removesuffix(self, suffix: str):
+        if suffix == "":
+            return self
         ends_with = pc.ends_with(self._pa_array, pattern=suffix)
         removed = pc.utf8_slice_codeunits(self._pa_array, 0, stop=-len(suffix))
         result = pc.if_else(ends_with, removed, self._pa_array)
         return self._from_pyarrow_array(result)
 
+
     def _str_startswith(
         self, pat: str | tuple[str, ...], na: Scalar | lib.NoDefault = lib.no_default
     ):