Refactor chef roles for Gitaly to be the same for gstg and gprd

Problem

At the moment gstg and gprd roles for ServiceGitaly have a different hierarchy, for example there is no gitlay-common in gstg.

Having different roles in gstg and gprd make it hard to test the rollout of configuration changes without testing it in staging, and we end up testing blindly in production since we don't have a dry-run mode in production to find out the changes that it will make.

gprd

graph TD
    gprd-base-stor-gitaly-common-->gprd-base-stor-gitaly-cny
    gprd-base-stor-gitaly-common-->gprd-base-stor-gitaly
    gprd-base-stor-gitaly-->gprd-base-stor-gitaly-hdd
    gprd-base-stor-gitaly-->gprd-base-stor-gitaly-praefect
    gprd-base-stor-gitaly-->gprd-base-stor-gitaly-marquee

    gprd-base-stor-praefect

gstg

graph TD
    gstg-base-stor-gitaly-->gstg-base-stor-gitaly-cny
    gstg-base-stor-gitaly-->gstg-base-stor-gitaly-hdd
    gstg-base-stor-gitaly-->gstg-base-stor-gitaly-zfs
    gstg-base-stor-gitaly-->gstg-base-stor-gitaly-praefect-cny

    gstg-base-stor-praefect
    gstg-base-stor-praefect-cny