changed already exsisitng function

Signed-off-by: yashneet vinayak <yashneet@amazon.com>

contrib/babelfishpg_tsql/sql/sys_function_helpers.sql

@@ -9638,7 +9638,7 @@ BEGIN
 END;
 $BODY$
 LANGUAGE plpgsql
-IMMUTABLE;
+STABLE;
 
 CREATE OR REPLACE FUNCTION sys.babelfish_conv_helper_to_datetime(IN arg sys.VARCHAR,
 															IN try BOOL,

contrib/babelfishpg_tsql/sql/upgrades/babelfishpg_tsql--3.9.0--3.10.0.sql

@@ -106,23 +106,6 @@ $BODY$
 LANGUAGE plpgsql
 IMMUTABLE;
 
-CREATE OR REPLACE FUNCTION sys.babelfish_conv_helper_to_datetime(IN arg TEXT,
-                                                            IN try BOOL,
-													        IN p_style NUMERIC DEFAULT 0)
-RETURNS sys.DATETIME
-AS
-$BODY$
-BEGIN
-    IF try THEN
-	    RETURN sys.babelfish_try_conv_string_to_datetime('DATETIME', arg, p_style);
-    ELSE
-        RETURN sys.babelfish_conv_string_to_datetime('DATETIME', arg, p_style);
-    END IF;
-END;
-$BODY$
-LANGUAGE plpgsql
-IMMUTABLE;
-
 -- After upgrade, always run analyze for all babelfish catalogs.
 CALL sys.analyze_babelfish_catalogs();