### 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)

gen->write_assert(condition, message);
				if (condition.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
					codegen.generator->pop_temporary();
				}
				if (message.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
					codegen.generator->pop_temporary();
				}
#endif
			} break;
			case GDScriptParser::Node::BREAKPOINT: {
#ifdef DEBUG_ENABLED
				gen->write_breakpoint();
#endif
			} break;
			case GDScriptParser::Node::VARIABLE: {
				const GDScriptParser::VariableNode *lv = static_cast<const GDScriptParser::VariableNode *>(s);
				
				GDScriptCodeGenerator::Address local = codegen.locals[lv->identifier->name];
				GDScriptDataType local_type = _gdtype_from_datatype(lv->get_datatype(), codegen.script);
				bool initialized = false;
				if (lv->initializer != nullptr) {
					GDScriptCodeGenerator::Address src_address = _parse_expression(codegen, err, lv->initializer);
					if (err) {
						return err;
					}
					if (lv->use_conversion_assign) {
						gen->write_assign_with_conversion(local, src_address);
					} else {
						gen->write_assign(local, src_address);
					}