### Godot version

3fa8fad

### System information

Debian Linux x86

### Issue description

#79205 introduces a regression to the way rpc configs are inherited, causing this error:

```
ERROR: Unable to get the RPC configuration for the function "foo" at path: "/root/Node". This happens when the method is missing or not marked for RPCs in the local script.
```

even though the function exists both in the server and the client. If you `print(self.foo)`, it even tells you that it's rpc: `Node(client.gd)::foo (rpc)` 

Before #79205 `GdScriptCompiler::_populate_class_members` used `GDScriptCache::get_full_script` to access the base script. This causes the parent script to be compiled (if it is not compiled yet), which in turn initializes the `rpc_config` property with a copy of the base value in [gdscript.cpp::_init_rpc_methods_properties](https://github.com/godotengine/godot/blob/3fa8fad26b97a8af20e7996b7e17d8f23fc04b89/modules/gdscript/gdscript.cpp#L1398-L1412)

However, `GDScriptCache::get_shallow_script` does not compile and thus does not initialize the `rpc_config` of the base script, causing the rpc functions not being included in the rpc config.

### Steps to reproduce

Extend a gdscript with a `@rpc` function annotation and try to do a network call:

server.gd:
```gdscript
extends Node

func _ready():
	var peer := ENetMultiplayerPeer.new()
	peer.create_server(1337)
	multiplayer.multiplayer_peer = peer

@rpc("any_peer") func foo():
	print("Server")
```

parent.gd:
```gdscript
extends Node

@rpc func foo(): pass
```

client.gd:
```gdscript
extends "parent.gd"

func _ready():
	var peer := ENetMultiplayerPeer.new()
	peer.create_client("localhost", 1337)
	multiplayer.connected_to_server.connect(func (): self.foo.rpc_id(1))
	multiplayer.multiplayer_peer = peer
```


### Minimal reproduction project

[test.zip](https://github.com/godotengine/godot/files/12215814/test.zip)

GLOBAL_DEF("debug/gdscript/warnings/enable", true);
	GLOBAL_DEF("debug/gdscript/warnings/exclude_addons", true);
	for (int i = 0; i < (int)GDScriptWarning::WARNING_MAX; i++) {
		GDScriptWarning::Code code = (GDScriptWarning::Code)i;
		Variant default_enabled = GDScriptWarning::get_default_value(code);
		String path = GDScriptWarning::get_settings_path_from_code(code);
		GLOBAL_DEF(GDScriptWarning::get_property_info(code), default_enabled);
	}
#endif 
}
GDScriptLanguage::~GDScriptLanguage() {
	singleton = nullptr;
}
void GDScriptLanguage::add_orphan_subclass(const String &p_qualified_name, const ObjectID &p_subclass) {
	orphan_subclasses[p_qualified_name] = p_subclass;
}
Ref<GDScript> GDScriptLanguage::get_orphan_subclass(const String &p_qualified_name) {
	HashMap<String, ObjectID>::Iterator orphan_subclass_element = orphan_subclasses.find(p_qualified_name);
	if (!orphan_subclass_element) {
		return Ref<GDScript>();
	}
	ObjectID orphan_subclass = orphan_subclass_element->value;
	Object *obj = ObjectDB::get_instance(orphan_subclass);
	orphan_subclasses.remove(orphan_subclass_element);
	if (!obj) {
		return Ref<GDScript>();
	}
	return Ref<GDScript>(Object::cast_to<GDScript>(obj));
}
Ref<GDScript> GDScriptLanguage::get_script_by_fully_qualified_name(const String &p_name) {