Draft: POC for automating the creation of patch release blog post MR

What does this MR do?

This MR along with gitlab-com/www-gitlab-com!94306 (closed) is for automatically creating a blog post MR when the /chatops run release prepare <patch_version> command is executed.

Approach:

1. release-tools triggers a pipeline in gitlab-com/www-gitlab-com> using a trigger token. The pipeline runs the rake task that generates the blog post file, which is then stored as a job artifact.
2. release-tools downloads the artifact file, commits it, and creates an MR.
3. release-tools edits the description of the patch release task issue to add a link to the blog post MR.

An alternative approach would be for release-tools to run the rake task locally. See !1621 (comment 742534316). I went with the trigger pipeline approach to minimize the internal details about www-gitlab-com that release-tools needs to know.

gitlab-com/gl-infra/delivery#186 (closed)

Author Check-list

• Has documentation been updated?