Remove highlighting from new issues

What does this MR do and why?

Removes highlight color on "new" issues

See related thread: #233045 (comment 1020470011)

tl;dr The green (new) issues is sort of a confusing feature. We'd like to try removing it altogether to see if we receive any feedback.

Screenshots or screen recordings

Before	After

How to set up and validate locally

• Create a new issue or task
• Go back and look at the main issue list
• Newly created issue should not have a green background

MR acceptance checklist

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