Only emit image painting events in debug & profile modes. (#118872)

* Only emit image painting events in debug & profile modes.

These events were being emitted in release mode, which was showing up in the
profiler for my app as taking up a noticeable amount of build time (still
well within the frame budget, but this code was near the top of the list).

* Review comment

packages/flutter/lib/src/painting/decoration_image.dart

@@ -599,7 +599,7 @@ void paintImage({
       return true;
     }());
     // Avoid emitting events that are the same as those emitted in the last frame.
-    if (!_lastFrameImageSizeInfo.contains(sizeInfo)) {
+    if (!kReleaseMode && !_lastFrameImageSizeInfo.contains(sizeInfo)) {
       final ImageSizeInfo? existingSizeInfo = _pendingImageSizeInfo[sizeInfo.source];
       if (existingSizeInfo == null || existingSizeInfo.displaySizeInBytes < sizeInfo.displaySizeInBytes) {
         _pendingImageSizeInfo[sizeInfo.source!] = sizeInfo;