fix optimizer histogram memory leak in KVCACHE

src/sql/resolver/ddl/ob_analyze_stmt_resolver.h

@@ -50,9 +50,6 @@ private:
                                  ObAnalyzeStmt &analyze_stmt);
   int resolve_sample_clause_info(const ParseNode *sample_clause_node,
                                  ObAnalyzeStmt &analyze_stmt);
-
-  int get_bucket_size(const ParseNode *node, int64_t &bucket_num);
-
   // disallow copy
   DISALLOW_COPY_AND_ASSIGN(ObAnalyzeStmtResolver);
 };