Settings: Remove 'Increase Timer Resolution' option

It's no longer needed since I switched to high-resolution waitable
timers, which are supported on Win10 1803+.

src/common/timer.cpp

@@ -135,7 +135,7 @@ void Timer::SleepUntil(Value value, bool exact)
     }
 
     // falling back to sleep... bad.
-    Sleep(static_cast<DWORD>(static_cast<u64>(diff) / 1000000));
+    Sleep(static_cast<DWORD>(ConvertValueToMilliseconds(diff)));
   }
 }