Update size and metrics after set_rich_text in TextPipeline::update_buffer (#22021)

# Objective

Rearrange the order that cosmic text's properties are set for improved
performance.

## Solution

Update size and metrics after `set_rich_text` in
`TextPipeline::update_buffer`

## Testing

yellow = this PR, red = main:

```
cargo run --example many_glyphs --features=trace_tracy,debug --release -- --recompute-text 
```

<img width="1610" height="605" alt="reorder"
src="https://github.com/user-attachments/assets/4819aa79-a147-45ab-8636-3e17f81462b2"
/>

<img width="1603" height="617" alt="reorder-measure-text"
src="https://github.com/user-attachments/assets/eb74569d-79e1-4138-9283-641eae8fd2ab"
/>

Author: ickshonpe

crates/bevy_text/src/pipeline.rs

@@ -191,7 +191,6 @@ impl TextPipeline {
 
         // Update the buffer.
         let buffer = &mut computed.buffer;
-        buffer.set_size(font_system, bounds.width, bounds.height);
 
         buffer.set_wrap(
             font_system,
@@ -213,11 +212,10 @@ impl TextPipeline {
 
         // Workaround for alignment not working for unbounded text.
         // See https://github.com/pop-os/cosmic-text/issues/343
-        if bounds.width.is_none() && justify != Justify::Left {
-            let dimensions = buffer_dimensions(buffer);
-            // `set_size` causes a re-layout to occur.
-            buffer.set_size(font_system, Some(dimensions.x), bounds.height);
-        }
+        let width = (bounds.width.is_none() && justify != Justify::Left)
+            .then(|| buffer_dimensions(buffer).x)
+            .or(bounds.width);
+        buffer.set_size(font_system, width, bounds.height);
 
         // Recover the spans buffer.
         spans.clear();