Revert "Prevent crashing if max_threads is zero."

This reverts commit a1788e0.

Author: WinnerWind

core/object/worker_thread_pool.cpp

@@ -780,7 +780,7 @@ void WorkerThreadPool::init(int p_thread_count, float p_low_priority_task_ratio)
 
 	runlevel = RUNLEVEL_NORMAL;
 
-	if (p_thread_count <= 0) {
+	if (p_thread_count < 0) {
 		p_thread_count = OS::get_singleton()->get_default_thread_pool_size();
 	}
 

doc/classes/ProjectSettings.xml

@@ -3404,7 +3404,7 @@
 			The ratio of [WorkerThreadPool]'s threads that will be reserved for low-priority tasks. For example, if 10 threads are available and this value is set to [code]0.3[/code], 3 of the worker threads will be reserved for low-priority tasks. The actual value won't exceed the number of CPU cores minus one, and if possible, at least one worker thread will be dedicated to low-priority tasks.
 		</member>
 		<member name="threading/worker_pool/max_threads" type="int" setter="" getter="" default="-1">
-			Maximum number of threads to be used by [WorkerThreadPool]. Value of [code]0[/code] or less means [code]1[/code] on Web, or a number of [i]logical[/i] CPU cores available on other platforms (see [method OS.get_processor_count]).
+			Maximum number of threads to be used by [WorkerThreadPool]. Value of [code]-1[/code] means [code]1[/code] on Web, or a number of [i]logical[/i] CPU cores available on other platforms (see [method OS.get_processor_count]).
 		</member>
 		<member name="xr/openxr/binding_modifiers/analog_threshold" type="bool" setter="" getter="" default="false">
 			If [code]true[/code], enables the analog threshold binding modifier if supported by the XR runtime.