[bug](function) fix conv function get wrong result as parse overflow (a…

…pache#38001)

```
mysql> select conv('ffffffffffffff', 24, 2);
+------------------------------------------------------------------+
| conv('ffffffffffffff', 24, 2)                                    |
+------------------------------------------------------------------+
| 1111111111111111111111111111111111111111111111111111111111111111 |
+------------------------------------------------------------------+

before get wrong result as 'ffffffffffffff' have beyond the max value of int64, so get max value: std::numeric_limits<int64_t>::max()


mysql> select conv('ffffffffffffff', 24, 2);
+------------------------------------------------------------------+
| conv('ffffffffffffff', 24, 2)                                    |
+------------------------------------------------------------------+
| 1011111001100011011111100110111101001101111010011011110100110111 |
+------------------------------------------------------------------+
now change it to parse as uint64_t could get result.
But if the value is still overflow, will get max value of uint64_t
```

be/src/vec/functions/function_conv.cpp

@@ -206,8 +206,12 @@ struct ConvStringImpl {
                                size_t index) {
         StringRef str = data_column->get_data_at(index);
         StringParser::ParseResult parse_res;
+        // select conv('ffffffffffffff', 24, 2);
+        // if 'ffffffffffffff' parse as int64_t will be overflow, will be get max value: std::numeric_limits<int64_t>::max()
+        // so change it parse as uint64_t, and return value could still use int64_t, in function decimal_to_base could handle it.
+        // But if the value is still overflow in uint64_t, will get max value of uint64_t
         int64_t decimal_num =
-                StringParser::string_to_int<int64_t>(str.data, str.size, src_base, &parse_res);
+                StringParser::string_to_int<uint64_t>(str.data, str.size, src_base, &parse_res);
         if (src_base < 0 && decimal_num >= 0) {
             result_null_map[index] = true;
             result_column->insert_default();

regression-test/data/nereids_p0/sql_functions/math_functions/test_conv.out

@@ -2,3 +2,12 @@
 -- !select --
 1111
 
+-- !select2 --
+1011111001100011011111100110111101001101111010011011110100110111
+
+-- !select3 --
+1111111111111111111111111111111111111111111111111111111010001001
+
+-- !select4 --
+18446744073709551615
+

regression-test/suites/nereids_p0/sql_functions/math_functions/test_conv.groovy

@@ -19,5 +19,9 @@ suite("test_conv") {
     sql "SET enable_nereids_planner=true"
     sql "SET enable_fallback_to_original_planner=false"
     qt_select "SELECT CONV(15,10,2)"
+    qt_select2 "select conv('ffffffffffffff', 24, 2);"
+    qt_select3 "select conv('-ff', 24, 2);"
+    // if beyond the max value of uint64, use max_uint64 as res
+    qt_select4 "select conv('fffffffffffffffffffffffffffffffff', 24, 10);"
 }