### Godot version

v4.0.3.stable.mono.official [5222a99f5]

### System information

macOS Monterey 12.6.6 (21G646)

### Issue description

When creating a tileset by code with custom data layers, removing a layer with `remove_custom_data_layer` does not update the name-to-layer mapping; `get_custom_data_layer_by_name` will continue to return that layer's original index.

This has a downstream effect of causing TileData objects attempting to use `get_custom_data('Layer B')` to return invalid data (whatever custom data is now in Layer B's old index; e.g. Layer C).

I would expect that after using `remove_custom_data_layer`, I would be able to still use `get_custom_data_layer_by_name` on that tileset.

### Steps to reproduce

Run this code to see that getting Layer B by name after removing the first layer continues to return its original index (1) when in reality it is now at index 0.
```
	var tileset:TileSet = TileSet.new()

	tileset.add_custom_data_layer()
	tileset.set_custom_data_layer_name(0, 'Layer A')
	tileset.set_custom_data_layer_type(0, TYPE_INT)

	tileset.add_custom_data_layer()
	tileset.set_custom_data_layer_name(1, 'Layer B')
	tileset.set_custom_data_layer_type(1, TYPE_STRING)

	print('Layer index 0 name : ', tileset.get_custom_data_layer_name(0)) # Layer A
	print('Layer index 1 name : ', tileset.get_custom_data_layer_name(1)) # Layer B
	print('Layer B is on index : ', tileset.get_custom_data_layer_by_name("Layer B")) # 1

	print('----- removing custom data layer 0 -----')
	tileset.remove_custom_data_layer(0)

	print('Layer index 0 name : ', tileset.get_custom_data_layer_name(0)) # Layer B
	print('Layer index 1 name : ', tileset.get_custom_data_layer_name(1)) # prints an error, as expected
	print('Layer B is on index : ', tileset.get_custom_data_layer_by_name("Layer B")) # returns 1 still! should return 0.
```

### Minimal reproduction project

[RemoveCustomDataLayer.zip](https://github.com/godotengine/godot/files/11804762/RemoveCustomDataLayer.zip)

ERR_FAIL_COND(p_new_source_id < 0);
	ERR_FAIL_COND_MSG(!sources.has(p_source_id), vformat("Cannot change TileSet atlas source ID. No tileset atlas source with id %d.", p_source_id));
	if (p_source_id == p_new_source_id) {
		return;
	}
	ERR_FAIL_COND_MSG(sources.has(p_new_source_id), vformat("Cannot change TileSet atlas source ID. Another atlas source exists with id %d.", p_new_source_id));
	sources[p_new_source_id] = sources[p_source_id];
	sources.erase(p_source_id);
	source_ids.erase(p_source_id);
	source_ids.push_back(p_new_source_id);
	source_ids.sort();
	_compute_next_source_id();
	terrains_cache_dirty = true;
	emit_changed();
}
bool TileSet::has_source(int p_source_id) const {
	return sources.has(p_source_id);
}
Ref<TileSetSource> TileSet::get_source(int p_source_id) const {
	ERR_FAIL_COND_V_MSG(!sources.has(p_source_id), nullptr, vformat("No TileSet atlas source with id %d.", p_source_id));
	return sources[p_source_id];
}
int TileSet::get_source_count() const {
	return source_ids.size();
}
int TileSet::get_source_id(int p_index) const {