… set (#15417)

Relates to #15416

This PR modifies the provisioner helm chart logic:
- Previously, when both provisionerDaemon.keySecretName and provisionerDaemon.pskSecretName
  were both set, we would fail to install the chart. This required users to have an obnoxious workaround
  in place where setting provisionerDaemon.pskSecretName="" was required in order to use provisioner
  keys. We now check for pskSecretName being set to the default value when keySecretName is also specified,
  and switch to provisioner key authentication instead of PSK. The previous workaround is still supported.
- We also had omitted to check for provisionerd.Tags being set along with provisionerDaemon.keySecretName.
  This would result in a crashlooping provisioner deployment, as setting both of these configuration options is
  not allowed. We now fast-fail the Helm deployment if we detect this scenario.

(cherry picked from commit 6781b0f)

This PR:
- Updates the table in `docs/admin/provisioners.md` to include highlight
multi-org changes
- Updates the instructions for the provisionerd helm chart when using
provisioner keys

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Co-authored-by: Ben Potter <ben@coder.com>
(cherry picked from commit 9f05b19)