### Godot version

any version after 74458b6

### System information

Linux x64, but likely irrelevant

### Issue description

OpenXR action maps are not properly exported in recent builds of Godot 4: the `.res` file is small and does no longer seem to contain anything of use. In-game, no actions are passed on to OpenXR (obviously).

I bisected the issue down to https://github.com/godotengine/godot/commit/74458b6e9bed0f28db3374c7406eacbcf4b09b9d, which was merged in #70377.

### Steps to reproduce

1. Delete any previous export files (`.godot/exported/*/*.pkg`)
2. Perform an export (I did one for Android, but it likely works with anything)
3. Observe OpenXR actions not working in the export (error spam 'sync_action_sets: Condition "active_sets.size() == 0"'), and the exported action map file being very small (`.godot/exported/*/*.pkg`, from a few tens of kilobytes down to 296 bytes)

### Minimal reproduction project

Any OpenXR project can be used, such as https://github.com/BastiaanOlij/godot4_openxr_demo
uint32_t pack_flags = 0;
	bool enc_pck = p_preset->get_enc_pck();
	bool enc_directory = p_preset->get_enc_directory();
	if (enc_pck && enc_directory) {
		pack_flags |= PACK_DIR_ENCRYPTED;
	}
	f->store_32(pack_flags); 
	uint64_t file_base_ofs = f->get_position();
	f->store_64(0); 
	for (int i = 0; i < 16; i++) {
		
		f->store_32(0);
	}
	f->store_32(pd.file_ofs.size()); 
	Ref<FileAccessEncrypted> fae;
	Ref<FileAccess> fhead = f;
	if (enc_pck && enc_directory) {
		String script_key = p_preset->get_script_encryption_key().to_lower();
		Vector<uint8_t> key;
		key.resize(32);
		if (script_key.length() == 64) {
			for (int i = 0; i < 32; i++) {
				int v = 0;
				if (i * 2 < script_key.length()) {
					char32_t ct = script_key[i * 2];
					if (is_digit(ct)) {
						ct = ct - '0';
					} else if (ct >= 'a' && ct <= 'f') {
						ct = 10 + ct - 'a';
					}