### 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)

Ref<GDScript> sqscr = p_resource;
	ERR_FAIL_COND_V(sqscr.is_null(), ERR_INVALID_PARAMETER);
	String source = sqscr->get_source_code();
	{
		Error err;
		Ref<FileAccess> file = FileAccess::open(p_path, FileAccess::WRITE, &err);
		ERR_FAIL_COND_V_MSG(err, err, "Cannot save GDScript file '" + p_path + "'.");
		file->store_string(source);
		if (file->get_error() != OK && file->get_error() != ERR_FILE_EOF) {
			return ERR_CANT_CREATE;
		}
	}
	if (ScriptServer::is_reload_scripts_on_save_enabled()) {
		GDScriptLanguage::get_singleton()->reload_tool_script(p_resource, true);
	}
	return OK;
}
void ResourceFormatSaverGDScript::get_recognized_extensions(const Ref<Resource> &p_resource, List<String> *p_extensions) const {
	if (Object::cast_to<GDScript>(*p_resource)) {
		p_extensions->push_back("gd");
	}
}
bool ResourceFormatSaverGDScript::recognize(const Ref<Resource> &p_resource) const {
	return Object::cast_to<GDScript>(*p_resource) != nullptr;
}