Update Deprecations copy in release post template
Related to #12451 (closed).
Moving forward, we will not list deprecations on the release post page, they will only be in Docs as SSOT. Therefore the release post template should always just say the following 14.6 14.4 onward:
New deprecations and the complete list of all features that are currently deprecated can be viewed in the
[GitLab documentation](https://docs.gitlab.com/ee/update/deprecations.html)
Edited by Farnoosh Seifoddini