Merge branch 'pedropombeiro/459999/add-desired_sharding_key' into 'master'

Add desired_sharding_key to p_ci_runner_machine_builds.yml

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/163492



Merged-by: Tianwen Chen <tchen@gitlab.com>
Approved-by: Fred Reinink <freinink@gitlab.com>
Approved-by: Tianwen Chen <tchen@gitlab.com>
Approved-by: Omar Qunsul <oqunsul@gitlab.com>
Reviewed-by: Pedro Pombeiro <noreply@pedro.pombei.ro>
Co-authored-by: Pedro Pombeiro <noreply@pedro.pombei.ro>