Fix flickering on macOS 26 when tracy is enabled (#22365)

# Objective

- Fix flickering/strobing when using tracy.
- Close #22257 

## Solution

- Disable writing timestamps in command encoders on macOS.

## Testing

- Can no longer repro with `cargo run --example bloom_3d
--features=trace_tracy`
- `bevy_bistro_scene` also no longer exhibits the flickering

Author: aevyrie

crates/bevy_render/src/diagnostic/internal.rs

@@ -643,6 +643,13 @@ pub trait WriteTimestamp {
 
 impl WriteTimestamp for CommandEncoder {
     fn write_timestamp(&mut self, query_set: &QuerySet, index: u32) {
+        if cfg!(target_os = "macos") {
+            // When using tracy (and thus this function), rendering was flickering on macOS Tahoe.
+            // See: https://github.com/bevyengine/bevy/issues/22257
+            // The issue seems to be triggered when `write_timestamp` is called very close to frame
+            // presentation.
+            return;
+        }
         CommandEncoder::write_timestamp(self, query_set, index);
     }
 }