[SPARK-48591][PYTHON] Simplify the if-else branches with F.lit

### What changes were proposed in this pull request?
Simplify the if-else branches with `F.lit` which accept both Column and non-Column input

### Why are the changes needed?
code clean up

### Does this PR introduce _any_ user-facing change?
No, internal minor refactor

### How was this patch tested?
CI

### Was this patch authored or co-authored using generative AI tooling?
No

Closes #46946 from zhengruifeng/column_simplify.

Authored-by: Ruifeng Zheng <ruifengz@apache.org>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>

Author: zhengruifeng

python/pyspark/sql/connect/column.py

@@ -27,13 +27,15 @@
     Any,
     Union,
     Optional,
+    cast,
 )
 
 from pyspark.sql.column import Column as ParentColumn
 from pyspark.errors import PySparkTypeError, PySparkAttributeError, PySparkValueError
 from pyspark.sql.types import DataType
 
 import pyspark.sql.connect.proto as proto
+from pyspark.sql.connect.functions import builtin as F
 from pyspark.sql.connect.expressions import (
     Expression,
     UnresolvedFunction,
@@ -308,14 +310,12 @@ def when(self, condition: ParentColumn, value: Any) -> ParentColumn:
                 message_parameters={},
             )
 
-        if isinstance(value, Column):
-            _value = value._expr
-        else:
-            _value = LiteralExpression._from_value(value)
-
-        _branches = self._expr._branches + [(condition._expr, _value)]
-
-        return Column(CaseWhen(branches=_branches, else_value=None))
+        return Column(
+            CaseWhen(
+                branches=self._expr._branches + [(condition._expr, F.lit(value)._expr)],
+                else_value=None,
+            )
+        )
 
     def otherwise(self, value: Any) -> ParentColumn:
         if not isinstance(self._expr, CaseWhen):
@@ -328,12 +328,12 @@ def otherwise(self, value: Any) -> ParentColumn:
                 "otherwise() can only be applied once on a Column previously generated by when()"
             )
 
-        if isinstance(value, Column):
-            _value = value._expr
-        else:
-            _value = LiteralExpression._from_value(value)
-
-        return Column(CaseWhen(branches=self._expr._branches, else_value=_value))
+        return Column(
+            CaseWhen(
+                branches=self._expr._branches,
+                else_value=cast(Expression, F.lit(value)._expr),
+            )
+        )
 
     def like(self: ParentColumn, other: str) -> ParentColumn:
         return _bin_op("like", self, other)
@@ -457,14 +457,11 @@ def isin(self, *cols: Any) -> ParentColumn:
         else:
             _cols = list(cols)
 
-        _exprs = [self._expr]
-        for c in _cols:
-            if isinstance(c, Column):
-                _exprs.append(c._expr)
-            else:
-                _exprs.append(LiteralExpression._from_value(c))
-
-        return Column(UnresolvedFunction("in", _exprs))
+        return Column(
+            UnresolvedFunction(
+                "in", [self._expr] + [cast(Expression, F.lit(c)._expr) for c in _cols]
+            )
+        )
 
     def between(
         self,
@@ -554,10 +551,8 @@ def __getitem__(self, k: Any) -> ParentColumn:
                     message_parameters={},
                 )
             return self.substr(k.start, k.stop)
-        elif isinstance(k, Column):
-            return Column(UnresolvedExtractValue(self._expr, k._expr))
         else:
-            return Column(UnresolvedExtractValue(self._expr, LiteralExpression._from_value(k)))
+            return Column(UnresolvedExtractValue(self._expr, cast(Expression, F.lit(k)._expr)))
 
     def __iter__(self) -> None:
         raise PySparkTypeError(