Release Notes: rm all RSS linked images (#5112)

* Release Notes: replace RSS image with CSS button

* unified light/dark mode

* rm pop-out effect

* rm dropdown

* added version with plain linked text

* revert rn

* rm RSS linked icons from all blog posts

* Update blog-csoar/2025-01-03-application-update.md

* Update blog-csoar/2025-01-03-application-update.md

* Remove RSS logo from Cloud SIEM note

* Remove RSS logo from Service release note

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Co-authored-by: John Pipkin <[email protected]>

Author: kimsauce