RedisModule_ResetDataset should not clear the functions. (#11268)

As mentioned on docs, `RM_ResetDataset` Performs similar operation to FLUSHALL.
As FLUSHALL do not clean the function, `RM_ResetDataset` should not clean the functions
as well.

(cherry picked from commit d2ad01ab3e)

tests/unit/moduleapi/misc.tcl

@@ -44,6 +44,16 @@ start_server {tags {"modules"}} {
         assert_equal [r test.dbsize] 0
     }
 
+    test {test RedisModule_ResetDataset do not reset functions} {
+        r function load {#!lua name=lib
+            redis.register_function('test', function() return 1 end)
+        }
+        assert_equal [r function list] {{library_name lib engine LUA functions {{name test description {} flags {}}}}}
+        r test.flushall
+        assert_equal [r function list] {{library_name lib engine LUA functions {{name test description {} flags {}}}}}
+        r function flush
+    }
+
     test {test module keyexists} {
         r set x foo
         assert_equal 1 [r test.keyexists x]