windows: Update WindowsDisplay::frequency() (#10476)

A subsequent update introduced the `HMONITOR` value to the
`WindowsDisplay` struct, eliminating the need for polling to retrieve
this value.

Release Notes:

- N/A

crates/gpui/src/platform/windows/display.rs

@@ -121,10 +121,7 @@ impl WindowsDisplay {
     }
 
     pub(crate) fn frequency(&self) -> Option<u32> {
-        available_monitors()
+        get_monitor_info(self.handle).ok().and_then(|info| {
-            .get(self.display_id.0 as usize)
-            .and_then(|hmonitor| get_monitor_info(*hmonitor).ok())
-            .and_then(|info| {
             let mut devmode = DEVMODEW::default();
             unsafe {
                 EnumDisplaySettingsW(