Optimizations from server profile (#38290)

* Properly cache regexes in chat sanitization/accents

Wow I wonder if `new Regex()` has a cost to it *looks at server profile*.

* Avoid lag caused by Tippy command completions

CompletionHelper.PrototypeIDs explicitly says *not* to use it with EntityPrototype. Unsurprisingly, reporting a completion result for every entity prototype in the game is a *bad idea*.

* Add active count metrics to some high-load systems

Mover & NPCs

I suspect the thing that caused the Leviathan round to shit itself on performance is NPC spam in space or something. So let's verify that.

* Enable parallel processing on pow3r again

Originally disabled due to a theory of it causing bugs, it was re-enabled on Vulture, and I'm not aware of it having caused any issues there.

* Replace hashset with bitflags for AtmosMonitor alert types.

Allocating these hashsets was like 20% of the CPU of atmos, somehow.

* Cache HashSet used for space movement collider checks

Turns out this was a ton of server allocations. Huh.

Content.Server/Atmos/Monitor/Components/AtmosAlarmableComponent.cs

@@ -48,7 +48,7 @@ public sealed partial class AtmosAlarmableComponent : Component
     public HashSet<string> SyncWithTags { get; private set; } = new();
 
     [DataField("monitorAlertTypes")]
-    public HashSet<AtmosMonitorThresholdType>? MonitorAlertTypes { get; private set; }
+    public AtmosMonitorThresholdTypeFlags MonitorAlertTypes { get; private set; }
 
     /// <summary>
     ///     If this device should receive only. If it can only