Use group clusters when deploying (DeploymentPlatform)

What does this MR do?

• Creates KubenernetesNamespace for each project in group cluster

• Updates DeploymentPlatform to use group level clusters. EE Merge Request

• If for any reason the project does not have a KubernetesNamespace for the group cluster, then we will not return any KUBE_TOKEN

DeploymentPlatform algorithm

1. Project-level cluster trumps group-level cluster, that is, if there's an env scope match, project level always wins.

2. Sub-groups will determine which cluster to use by looking at closest ancestor with a matching env scope pattern.

Notes

NOTE: This MR also introduces a hierarchy_order option to Gitlab::GroupHierarchy which enables us to now explicitly order the query.

NOTE: This MR also enables group_clusters FF by default

There is a subsequent MR which depends on this MR

What are the relevant issue numbers?

#34758 (closed), #53592 (closed)

Tasks

• Combine deploy_group_clusters and group_clusters flags
• Add feature flag
• Create kubernetes namespace for projects in group on cluster creation
• Create kubernetes namespace on project creation - Projects::CreateService (Projects::ForkService calls out to CreateService)
• Create kubernetes namespace + (make delete for old kubernetes namespace) on project transfer / removal from group - Projects::TransferService
• clusters_kubernetes_namespaces already nullifies project on project delete
• Send KUBE_TOKEN from clusters_kubernetes_namespaces for group cluster
• Refresh service part 1 - add missing namespaces
• [-] Refresh service part 2 - Clean up old kubernetes namespace - Follow up in https://gitlab.com/gitlab-org/gitlab-ce/issues/53591
• KUBE_TOKEN - only return KUBE_TOKEN for the kubernetes namespace for the project (and not other projects!)
• create or update k8s resources in create_service_account_service.rb

Testing / Screenshots

• Make a group cluster
  • Add a group CI variable for AUTO_DEVOPS_DOMAIN
  • Run auto devops pipeline on a project in the group - Expect deploy to group cluster

• make a project cluster, set AUTO_DEVOPS_DOMAIN variable at project level
  • Enable group cluster
  • Run auto devops pipeline - Expect deploy to project cluster

• Disable group cluster and project cluster (Toggle OFF)
  • Run auto devops pipeline again - Expect no production job

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated - https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/22804
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• [-] Conforms to the style guides
• Conforms to the database guides