List and link deprecations from 14.4 forward

Why is this change being made?

Since 14.3, deprecations have been added to the gitlab project instead of www-gitlab-com. With that change, individual deprecations were no longer listed in the Release Post.

!99357 (closed) provided a proof of concept to add deprecations in 14.4+

gitlab-org/gitlab!81199 creates a rake task allowing the Release Post Manager to build an index of deprecations for a given milestone. That file can then be added to this project in the corresponding data/deprecations folder so that the Release Post can once again provide details on deprecations within the post.

This MR modifies the release post template so that only the name of the deprecation appears and is linked to the entry in GitLab Docs as requested.

Release Post history for quick check

• 14.8
• 14.7
• 14.6
• 14.5
• 14.4 (no deprecations)
• 14.3
• 14.2

Author Checklist

• Provided a concise title for the MR
• Added a description to this MR explaining the reasons for the proposed change, per say-why-not-just-what
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  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

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