[6.x] Ensure images are refreshed properly after cropping

[duncanmcclean]

This pull request fixes an issue where cropped images weren't updating in the asset editor after replacing the original file.

This was happening because the bustAndReloadImageCaches callback had two problems:

1. Using forEach with an async callback doesn't actually await the operations - the callback returns immediately while fetches happen in the background
2. Reassigning img.src = url to the same value doesn't reliably trigger a re-fetch since browsers may optimize this as a no-op

This PR fixes it by:

• Using a for...of loop instead of forEach to properly await each fetch operation
• Calling removeAttribute('src') before reassigning the src, which forces the browser to re-fetch from the (now updated) HTTP cache

Before

CleanShot.2026-03-16.at.11.12.28.mp4

After

CleanShot.2026-03-16.at.11.11.20.mp4

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Fixes #14155

Note: I could only reproduce this issue in Safari - Chrome refreshed images as expected.