Migrate v1.ScyllaCluster to in-operator integration with global ScyllaDB Manager instance

[rzetelskik]

Requires

• Support v1alpha1.ScyllaDBDatacenter registration with global ScyllaDB Manager instance #2570
• Support backup and repair task scheduling for v1alpha1.ScyllaDBDatacenter #2571

Acceptance criteria

• Extend ScyllaCluster migration controller to create ScyllaDBManagerTask objects and mark underlying ScyllaDBDatacenters for registration with global ScyllaDB Manager instance
  • Includes backpropagation of statuses
  • Includes backwards compatibility with ScyllaCluster API
• Ensure that satisfactory regression test coverage exists for the new mechanism of reconciliation of cluster registration and task scheduling for ScyllaClusters
• Drop manager-controller from global ScyllaDB Manager manifests