Move create_github_webhook Sidekiq queue

REF: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4762//diffs#note_61925805

This queue should be removed from https://dev.gitlab.org/cookbooks/chef-repo/blob/master/roles/gitlab-base-be-sidekiq-realtime.json and added to https://dev.gitlab.org/cookbooks/chef-repo/blob/master/roles/gitlab-base-be-sidekiq-asap.json one this MR is merged, so that it's executed ASAP after project creation.