staging: Test swh.graph workload in kubernetes

Following notes from [1]

• Design deployment document [2]
• swh/infra/ci-cd/swh-charts!459 (merged): Add graph template in swh charts so it can run in kubernetes
• swh/infra/ci-cd/swh-charts!459 (merged): Test it through local-cluster
• swh/infra/ci-cd/swh-charts!474 (closed): Deploy and test in next-version cluster (& adapt papercuts)
• swh/infra/ci-cd/swh-charts!459 (merged): Merge graph template
• Deploy in next-version
• swh/infra/ci-cd/swh-charts!484 (merged): Fix ingress communication between rpc/grpc instance (discovered in next-version)
• swh/infra/ci-cd/swh-charts!485 (merged): Deploy in staging cluster
• Add blackbox monitoring on graph instances

[2] https://hedgedoc.softwareheritage.org/mOk8M7znToWeZoMTiMb1Gw#

[1] #5381 (closed)