### 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)

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	virtual String get_class_icon_path() const override;
#endif 
	virtual Error reload(bool p_keep_state = false) override;
	virtual void set_path(const String &p_path, bool p_take_over = false) override;
	String get_script_path() const;
	Error load_source_code(const String &p_path);
	bool get_property_default_value(const StringName &p_property, Variant &r_value) const override;
	virtual void get_script_method_list(List<MethodInfo> *p_list) const override;
	virtual bool has_method(const StringName &p_method) const override;
	virtual MethodInfo get_method_info(const StringName &p_method) const override;
	virtual void get_script_property_list(List<PropertyInfo> *p_list) const override;
	virtual ScriptLanguage *get_language() const override;
	virtual int get_member_line(const StringName &p_member) const override {
#ifdef TOOLS_ENABLED
		if (member_lines.has(p_member)) {
			return member_lines[p_member];
		}
#endif
		return -1;
	}
	virtual void get_constants(HashMap<StringName, Variant> *p_constants) override;
	virtual void get_members(HashSet<StringName> *p_members) override;
	virtual const Variant get_rpc_config() const override;
	void unload_static() const;
#ifdef TOOLS_ENABLED
	virtual bool is_placeholder_fallback_enabled() const override { return placeholder_fallback_enabled; }