Allow configuration of securityContext user/group on all deployments with persistent volumes
This was already done for gitaly here: https://gitlab.com/charts/gitlab/merge_requests/473
But should also be done for minio and redis.
Some user's persistent volumes have unique constraints, that require them to use root to write to the volumes. While we will allow them to specify any user id in these configs, we expect only our defaults, and 0 (root), will work with the default gitlab images.
This change is meant to allow the root user workaround.