### 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)

void GDScriptAnalyzer::reduce_expression(GDScriptParser::ExpressionNode *p_expression, bool p_is_root) {
	
	if (p_expression == nullptr) {
		return;
	}
	if (p_expression->reduced) {
		
		return;
	}
	p_expression->reduced = true;
	switch (p_expression->type) {
		case GDScriptParser::Node::ARRAY:
			reduce_array(static_cast<GDScriptParser::ArrayNode *>(p_expression));
			break;
		case GDScriptParser::Node::ASSIGNMENT:
			reduce_assignment(static_cast<GDScriptParser::AssignmentNode *>(p_expression));
			break;
		case GDScriptParser::Node::AWAIT:
			reduce_await(static_cast<GDScriptParser::AwaitNode *>(p_expression));
			break;
		case GDScriptParser::Node::BINARY_OPERATOR:
			reduce_binary_op(static_cast<GDScriptParser::BinaryOpNode *>(p_expression));
			break;
		case GDScriptParser::Node::CALL:
			reduce_call(static_cast<GDScriptParser::CallNode *>(p_expression), false, p_is_root);
			break;
		case GDScriptParser::Node::CAST:
			reduce_cast(static_cast<GDScriptParser::CastNode *>(p_expression));
			break;
		case GDScriptParser::Node::DICTIONARY: