Fix: Preserve Redirection Links for Images in Emails

[MyvTsv]

• I have read the CONTRIBUTING document.
• I have performed a self-review of my code.
• I have added tests that prove my fix is effective or that my feature works.

Description

It fixes !35308

This PR fixes an issue where the redirect link associated with an image sent via the GLPI collector was removed. When someone sent an image with a redirect link, the link was deleted, preventing the redirect from working. Therefore, in a ticket when t-one clicked on the image, GLPI redirected us to it and not to the URL that was associated with it.

[stonebuzz]

Maybe a new test should be added (instead of update it) to test the regex format (permissive now)

To test that it accepts any type of content before or after <img>, including HTML tags.

<a href="example.com">
  <span>Balise imbriquée</span>
  <img src="image.jpg" alt="Image" class="tag-class" />
</a>

<a href="example.com">
  Une image simple
  <img src="image.jpg" alt="Image" class="tag-class" />
  Plus de texte ici
</a>

<a href="example.com">
  <div>
    Contenu complexe
    <img src="image.jpg" class="tag-class" />
  </div>
</a>

[trasher]

I'm not sure I understand this fix... It talks about keeping redireciton link, and tests was adapted to drop one :D

Also, it seems the previous fix was successfully used by the customer; is this the same case as the "original" one?