Incorrect image transformation on copy/paste replaced with loading spinners

[Dunos]

Using the onLatexUpdate property to transform the images instead of relying on a node.js server running on the background to process those with MathJax (following this ticket), is causing some issues when the users copy/paste content that contains the images already generated. Some of those images are incorrectly replaced with a loading spinner instead (from the loadingImage inside the persistValidImages method).

I have attached a video to show how the onValueChange calls the callback method twice, the first one with the correct images, but then a second time with some spinners instead.

rich-text-editor-issue.mp4

The code we use to transofrm the images is pretty similar to the one we already shared on the mentioned ticket.

[Dunos]

@jan-aleksi this one is kind of related to the one you have work on before