### Godot version

v4.0.rc1.official [8843d9ad3]

### System information

Lubuntu

### Issue description

You can't use + or += to mutate typed arrays.

It seems to be not correctly getting the type information from the second operand.

An erudite poster on the discord puts it differently:
> it's more like operator + doesn't retain Array typing
> the syntax for Array Concatenation via operators, but the idea gets across i think


The error you see is:
```Trying to assign an array of type "Array" to a variable of type "Array[int]".```


### Steps to reproduce

```
	var Alice: Array[int] = [1,2,3]
	var Bob: Array[int] = [4,5,6]
	Alice += Bob
```
This will crash with the above error message.

### Minimal reproduction project

[plus_syntax_broken_demo_project.zip](https://github.com/godotengine/godot/files/10694514/plus_syntax_broken_demo_project.zip)

}
		if (ClassDB::get_signal(native, name, &method_info)) {
			
			p_identifier->set_datatype(make_signal_type(method_info));
			p_identifier->source = GDScriptParser::IdentifierNode::INHERITED_VARIABLE;
			return;
		}
		if (ClassDB::has_enum(native, name)) {
			p_identifier->set_datatype(make_native_enum_type(name, native));
			p_identifier->source = GDScriptParser::IdentifierNode::MEMBER_CONSTANT;
			return;
		}
		bool valid = false;
		int64_t int_constant = ClassDB::get_integer_constant(native, name, &valid);
		if (valid) {
			p_identifier->is_constant = true;
			p_identifier->reduced_value = int_constant;
			p_identifier->source = GDScriptParser::IdentifierNode::MEMBER_CONSTANT;
			
			StringName enum_name = ClassDB::get_integer_constant_enum(native, name);
			if (enum_name != StringName()) {
				p_identifier->set_datatype(make_native_enum_type(enum_name, native, false));
			} else {
				p_identifier->set_datatype(type_from_variant(int_constant, p_identifier));
			}
		}
	}
}
void GDScriptAnalyzer::reduce_identifier(GDScriptParser::IdentifierNode *p_identifier, bool can_be_builtin) {