[SPARK-21658][SQL][PYSPARK] Revert "[] Add default None for value in na.replace in PySpark"

This reverts commit 0fcde87.

See the discussion in [SPARK-21658](https://issues.apache.org/jira/browse/SPARK-21658),  [SPARK-19454](https://issues.apache.org/jira/browse/SPARK-19454) and #16793

Author: hyukjinkwon <[email protected]>

Closes #20496 from HyukjinKwon/revert-SPARK-21658.

(cherry picked from commit 551dff2)
Signed-off-by: gatorsmile <[email protected]>

Author: HyukjinKwon

python/pyspark/sql/dataframe.py

@@ -1577,16 +1577,6 @@ def replace(self, to_replace, value=None, subset=None):
         |null|  null|null|
         +----+------+----+
 
-        >>> df4.na.replace('Alice').show()
-        +----+------+----+
-        | age|height|name|
-        +----+------+----+
-        |  10|    80|null|
-        |   5|  null| Bob|
-        |null|  null| Tom|
-        |null|  null|null|
-        +----+------+----+
-
         >>> df4.na.replace(['Alice', 'Bob'], ['A', 'B'], 'name').show()
         +----+------+----+
         | age|height|name|
@@ -2055,7 +2045,7 @@ def fill(self, value, subset=None):
 
     fill.__doc__ = DataFrame.fillna.__doc__
 
-    def replace(self, to_replace, value=None, subset=None):
+    def replace(self, to_replace, value, subset=None):
         return self.df.replace(to_replace, value, subset)
 
     replace.__doc__ = DataFrame.replace.__doc__