Update Reduce operation type checks for consistency

- Changed string comparisons for reduce types in the MakeReduce method from "abs_sum" to "abssum" and "abs_max" to "absmax" for uniformity.
- This adjustment enhances the clarity and consistency of the reduce type handling in the codebase.

Author: LeiWang1999

src/op/reduce.h

@@ -60,11 +60,11 @@ class ReduceType : public ObjectRef {
     auto node = make_object<ReduceTypeNode>();
     if (type == "sum") {
       node->type = int(ReduceTypeEnum::kSum);
-    } else if (type == "abs_sum") {
+    } else if (type == "abssum") {
       node->type = int(ReduceTypeEnum::kAbsSum);
     } else if (type == "max") {
       node->type = int(ReduceTypeEnum::kMax);
-    } else if (type == "abs_max") {
+    } else if (type == "absmax") {
       node->type = int(ReduceTypeEnum::kAbsMax);
     } else if (type == "min") {
       node->type = int(ReduceTypeEnum::kMin);