Add swap total chart to memory stats graph in host stats dashboard
As the example for log-es2 node - https://performance.gitlab.net/dashboard/db/host-stats?panelId=7&fullscreen&var-node=log-es2.yakfn1tm2ndezdsfrwdtnnse1f.cx.internal.cloudapp.net&from=now-24h&to=now
FYI - @gl-infra @briann