Investigate failing `Tests_Image_Functions::test_wp_crop_image_with_url` test

[swissspidy]

This test seems to consistently fail on SiteGround. Example: ​https://make.wordpress.org/hosting/test-results/r57910/sitegroundbot-r57910/

The test tries to download & crop https://asdftestblog1.files.wordpress.com/2008/04/canola.jpg.

I wonder if we need to update the image URL like was done in [57908] / #60865. That would certainly be worth a try.

https://asdftestblog1.files.wordpress.com is used in 3 places, all of them should probably get updated.

Follow-up to #60865

Trac ticket: https://core.trac.wordpress.org/ticket/60907

[swissspidy]

In 57924:

Build/Test Tools: Update a few image URLs in HTTP and image cropping tests.

Follow-up to #60865 / [57903] where similar instances were recently updated due to an upstream change.

Particularly the test_wp_crop_image_with_url() test recently began to fail on some environments, likely because of the same change.

This updates the image URLs with the aim to bring more consistency and to get the test passing again more broadly.

Fixes #60907.

https://core.trac.wordpress.org/changeset/57924