Images using query parameters with an uncommon filetype are not recognized in insert from URL

[koopersmith]

We're being a little overzealous when trimming the query parameter, as we use the URL variable to double check that nothing has changed in the image's onload callback.

Patch fixes the issue, an example test URL is ​http://syndetics.com/index.php?isbn=9781423146193/lc.jpg&client=milwp&type=rn12

Simple coding error caused by accidentally overwriting a variable.

Please also strip off the : at the end, the Twitter API returns image files for different sizes like urlhere.com/image.jpg:large

(if it's not too late)

Removes a redundant !!

In 23110:

When inserting from URL in the media modal, retain query params and properly insert the caption code.

Props koopersmith
fixes #22796