The new tokens are managed centrally and have a longer expiry.
Administrators of the grafanabot account will be
notified of the pending expiry and the secret can be rotated centrally
without the need for a repository administrator to update their
secrets.
The existing repository secrets can safely be removed. The tokens for
those secrets will be removed by the end of this week.
Signed-off-by: Jack Baldry <jack.baldry@grafana.com>