Remove documentation for the deprecated dapr dashboard

[nelson-parente]

Summary

The dapr/dashboard repository is archived and the dapr dashboard CLI command along with the dashboard install are being removed from the Dapr CLI (companion CLI PR: dapr/cli#1647). This PR removes all corresponding documentation.

What was removed

• Deleted reference/cli/dapr-dashboard.md — the full command reference page
• reference/cli/cli-overview.md — removed dashboard from the command list and the Command Reference link; added aliases: [/reference/cli/dapr-dashboard/] so the old URL redirects here instead of 404ing
• getting-started/install-dapr-cli.md — removed "Run the Dapr dashboard" capability bullet and dashboard row from the CLI output block
• concepts/overview.md — removed the sentence describing the dashboard web UI
• reference/cli/dapr-init.md — removed the --dashboard-version flag row
• operations/hosting/kubernetes/kubernetes-deploy.md — removed the "Run the dashboard" step, the optional helm install dapr-dashboard section, and the dapr-dashboard-* line from the kubectl get pods output
• operations/hosting/kubernetes/cluster/setup-kind.md — removed the dapr dashboard -k -p 9999 port-forward step and the dapr-dashboard row from the dapr status -k output (addresses Remove Dapr dashboard references from KIND cluster set up steps #3735)
• operations/hosting/kubernetes/kubernetes-upgrade.md — removed dapr-dashboard-* from the kubectl get pods output
• operations/hosting/kubernetes/kubernetes-production.md — removed "The Dapr Dashboard (github.com/dapr/dashboard)" from the monitoring tools list
• operations/hosting/self-hosted/self-hosted-airgap.md — changed "CLI, runtime and dashboard" to "CLI and runtime"
• operations/security/mtls.md — removed the dapr-dashboard row from the dapr status -k example output
• operations/support/support-versioning.md — removed "dashboard" from versioning-scope wording and the section heading/body
• developing-applications/debugging/debug-k8s/debug-dapr-services.md — removed dapr-dashboard-* from the kubectl get pods output

Intentionally kept (not dapr/dashboard)

• All Grafana dashboard references (monitoring/observability pages)
• All Kubernetes Dashboard addon references (minikube, GKE cluster setup pages)
• All Diagrid Dashboard (ghcr.io/diagridio/diagrid-dashboard) references

Verification

• grep -rn "dapr-dashboard\|dapr dashboard\|daprio/dashboard\|dashboard-version\|github.com/dapr/dashboard" daprdocs/content/en/ — only remaining hit is the aliases: entry in cli-overview.md (intentional redirect)
• grep -rn "ref.*dashboard\|relref.*dashboard" daprdocs/content/en/ — same single hit, the aliases: entry; no {{< ref dapr-dashboard >}} shortcodes remain

Addresses #3735

Test plan

• Hugo build passes with no broken ref/relref shortcodes
• GET /reference/cli/dapr-dashboard/ returns a redirect to /reference/cli/ (alias works)
• No Grafana, Kubernetes Dashboard, or Diagrid Dashboard references were accidentally removed
• All edited markdown tables and code blocks are syntactically valid