### Godot version

508a5bf16ea50552c56539da4c96ea13fdf8853e

### System information

Windows 10, Intel i9-11900K

### Issue description

Godot runs fine in the Editor but any test run of a (3D) scene freezes the window up.
Even a test scene with just a single Node3D freezes.

All the test project runs fine with slightly older versions of master / Godot 4.1.

There are no errors but after bisecting it the problem points at changes from pr https://github.com/godotengine/godot/pull/76945 so properly some kind of thread deadlock.

![bisect_result](https://github.com/godotengine/godot/assets/52464204/85442c3c-7df2-43ca-85ef-e555055eec3d)

_edit_

Seems to be caused by ProjectSettings `threading/worker_pool/max_threads` set to 0 and `shader_compiler/shader_cache/enabled`=false

### Steps to reproduce

set ProjectSettings `threading/worker_pool/max_threads` to 0 and `shader_compiler/shader_cache/enabled`=false and testrun a scene from the Editor.

### Minimal reproduction project

[WorkerThreadPoolIssue.zip](https://github.com/godotengine/godot/files/11489032/WorkerThreadPoolIssue.zip)
#include "worker_thread_pool.h"
#include "core/os/os.h"
#include "core/os/thread_safe.h"
void WorkerThreadPool::Task::free_template_userdata() {
	ERR_FAIL_COND(!template_userdata);
	ERR_FAIL_COND(native_func_userdata == nullptr);
	BaseTemplateUserdata *btu = (BaseTemplateUserdata *)native_func_userdata;
	memdelete(btu);
}
WorkerThreadPool *WorkerThreadPool::singleton = nullptr;
void WorkerThreadPool::_process_task_queue() {
	task_mutex.lock();
	Task *task = task_queue.first()->self();
	task_queue.remove(task_queue.first());
	task_mutex.unlock();
	_process_task(task);
}
void WorkerThreadPool::_process_task(Task *p_task) {