Remove technical writer backups

Why is this change being made?

Follow up to: !103608 (merged).

With the new policy in place, we can formally remove TW backups from the site.

• Before: https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
• After: https://eread-remove-tw-backups.about.gitlab-review.app/handbook/engineering/ux/technical-writing/index.html#designated-technical-writers

CC @gl-docsteam

Approvals

Merge requests with changes to stages and groups and significant changes to categories need to be created, approved, and/or merged by each of the below:

• VP of Product @David
• The Product Director relevant to the affected Section(s)
• The Engineering Director relevant to the affected Section(s)
• Director of Product Design @vkarnes

The following people need to be on the merge request so they stay informed:

• Chief Technology Officer @edjdev
• Vice President of Development @clefelhocz1
• Vice President of Quality @meks
• Vice President of User Experience @clenneville
• The Product Marketing Manager relevant to the stage group(s)
• Senior Manager, Technical Writing @susantacker

After Approvals and Merge

• Create an issue in the triage-ops project to update GitLab Bot automation
• Mention the product group Technical Writer to update the documentation metadata
• Share MR in #product, #development, and relevant #s_, #g_, and #f_ slack channels