### 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)

while (subclass) {
			if (subclass->extends_used) {
				if (!subclass->extends_path.is_empty()) {
					if (subclass->extends.size() == 0) {
						get_global_class_name(subclass->extends_path, r_base_type);
						subclass = nullptr;
						break;
					} else {
						Vector<GDScriptParser::IdentifierNode *> extend_classes = subclass->extends;
						Ref<FileAccess> subfile = FileAccess::open(subclass->extends_path, FileAccess::READ);
						if (subfile.is_null()) {
							break;
						}
						String subsource = subfile->get_as_utf8_string();
						if (subsource.is_empty()) {
							break;
						}
						String subpath = subclass->extends_path;
						if (subpath.is_relative_path()) {
							subpath = path.get_base_dir().path_join(subpath).simplify_path();
						}
						if (OK != subparser.parse(subsource, subpath, false)) {
							break;
						}
						path = subpath;
						subclass = subparser.get_tree();
						while (extend_classes.size() > 0) {
							bool found = false;
							for (int i = 0; i < subclass->members.size(); i++) {
								if (subclass->members[i].type != GDScriptParser::ClassNode::Member::CLASS) {