[charts/metabase] fix label indentation in pdb

[tessig]

deploymentLabels should be intended exactly like pod labels.

If I understood correctly, Values should look like this:

  deploymentLabels:
    app-group: "metabase"
    app.kubernetes.io/name: "metabase"
    foo: bar

With the current template this results in an invalid pdb file

[pmint93]

Yeah, thanks for the fix