[bugfix](be) the config could not be modified on line (#46470)

This value is saved in some type description, could not be modified
online. User should restart BE after modify this value.
For example,
    static TypeDescriptor create_string_type() {
        TypeDescriptor ret;
        ret.type = TYPE_STRING;
        ret.len = config::string_type_length_soft_limit_bytes;
        return ret;
    }

Author: yiguolei

be/src/common/config.cpp

@@ -915,7 +915,7 @@ DEFINE_String(rpc_load_balancer, "rr");
 
 // a soft limit of string type length, the hard limit is 2GB - 4, but if too long will cause very low performance,
 // so we set a soft limit, default is 1MB
-DEFINE_mInt32(string_type_length_soft_limit_bytes, "1048576");
+DEFINE_Int32(string_type_length_soft_limit_bytes, "1048576");
 
 DEFINE_Validator(string_type_length_soft_limit_bytes,
                  [](const int config) -> bool { return config > 0 && config <= 2147483643; });