[BUG] TiDAGRequest contains wrongResidual Filter

[shiyuhang0]

This pr try to fix it #1308. But it still has some problems

Bug
execute spark.sql(select * from tidb_catalog.test.t where id > 1).explan:

== Physical Plan ==
*(1) ColumnarToRow
+- TiKV CoprocessorRDD{[table: t] TableScan, Columns: id@LONG, Residual Filter: [id@LONG GREATER_THAN 1], Not(IsNull(id@LONG)), PushDown Filter: [id@LONG GREATER_THAN 1], Not(IsNull(id@LONG)), KeyRange: [([t\200\000\000\000\000\000\000\226_r\000\000\000\000\000\000\000\000], [t\200\000\000\000\000\000\000\226_s\000\000\000\000\000\000\000\000])], Aggregates: , startTs: 433153046377922561}

Expected answer

• Residual Filter is the filter that pushdown to the coprocessor but can't pushdown to TiKV
• PushDown Filter is the filter that can pushdown to TiKV
  The info is wrong for the same value of Residual Filter and PushDown Filter, we need to show the correct info, for this example, Residual Filter should be null

[shiyuhang0]

/lifecycle frozen