🌱 fix duplicate machine tags.

[guettli]

What type of PR is this?

/kind bug Fixes a newly discovered bug.

What this PR does / why we need it:

Tags on HV machines are sometime duplicate.

{
  "deviceId": 15337,
 ...
 "tags": [
    "caphv-device-type=hvWorker",
    "caphv-cluster-name=hvtest-guettli",
    "caphv-cluster-hvtest-guettli=owned",
    "caphv-machine-name=hvtest-guettli-md-0-5pr2l",
    "caphv-cluster-name=hvtest-guettli",
    "caphv-machine-name=hvtest-guettli-md-0-5pr2l",
    "caphv-cluster-name=worker"
  ]
}

duplicate: caphv-cluster-name=hvtest-guettli caphv-machine-name=hvtest-guettli-md-0-5pr2l

And: caphv-cluster-name=worker looks strange.

Fixes #70