Artifacts generated by the docs:sid:amd64 job need to be retained longer
than for other jobs as they are used for building bind.isc.org contents.
If these artifacts are removed too quickly, pipelines in the pages/bind
GitLab project start failing, preventing content updates from being
published.  Increase lifetime of the relevant job artifacts to prevent
this from happening.

(cherry picked from commit 9751ba5a)