Remove pandas compatibility gating for dtypes in timdelta column (rapidsai#21258)

Remove pandas compatibility gating for dtypes in timdelta column

Authors:
  - GALI PREM SAGAR (https://github.com/galipremsagar)

Approvers:
  - Matthew Roeschke (https://github.com/mroeschke)

URL: rapidsai#21258

Author: galipremsagar

python/cudf/cudf/core/column/timedelta.py

@@ -87,11 +87,8 @@ def _validate_args(
         cls, plc_column: plc.Column, dtype: np.dtype
     ) -> tuple[plc.Column, np.dtype]:
         plc_column, dtype = super()._validate_args(plc_column, dtype)
-        if cudf.get_option("mode.pandas_compatible"):
-            if not dtype.kind == "m":
-                raise ValueError("dtype must be a timedelta numpy dtype.")
-        elif not (isinstance(dtype, np.dtype) and dtype.kind == "m"):
-            raise ValueError("dtype must be a timedelta numpy dtype.")
+        if dtype.kind != "m":
+            raise ValueError("dtype must be a timedelta dtype.")
         return plc_column, dtype
 
     def _clear_cache(self) -> None:
@@ -214,8 +211,7 @@ def _binaryop(self, other: ColumnBinaryOperand, op: str) -> ColumnBase:
                         other,
                         bool_fill_value=fill_value,
                     )
-                    if cudf.get_option("mode.pandas_compatible"):
-                        result = result.fillna(fill_value)
+                    result = result.fillna(fill_value)
                     return result
 
         if out_dtype is None: