Allow grafana discovery tag to be passed in via commandline

[Rachel Weber (rachelvweber)]

Allow grafana discovery tag to be passed in via commandline.

The requirement of the aro-hcp specific tag broke AMW discovery for ARO Classic.

[Copilot]

🟢 Approval recommended

The change is narrowly scoped, updates all known call sites, and includes validation plus a targeted test for the new CLI surface.

Pull request overview

This PR restores cross-subscription Azure Monitor Workspace discovery for ARO Classic by making the Resource Graph discovery tag key configurable via grafanactl (instead of being implicitly tied to the ARO-HCP-specific tag).

Changes:

• Add --discovery-tag-key base flag (default aroHCPPurpose) with input validation and a unit test.
• Thread the configured tag key into the Resource Graph discovery query used by clean, manage reconcile, and modify datasource reconcile.
• Extend pipeline types + JSON schema to allow discoveryTagKey to be specified for Grafana-related steps, and document the new behavior.

File summaries

File	Description
tools/grafanactl/README.md	Documents discovery-by-tag behavior and the new --discovery-tag-key flag.
tools/grafanactl/internal/azure/monitor.go	Adds a tag key field to Resource Graph discovery and uses it in the KQL query.
tools/grafanactl/cmd/modify/options.go	Passes the validated discovery tag key into the Resource Graph discovery client.
tools/grafanactl/cmd/manage/options.go	Passes the validated discovery tag key into the Resource Graph discovery client.
tools/grafanactl/cmd/clean/options.go	Passes the validated discovery tag key into the Resource Graph discovery client.
tools/grafanactl/cmd/base/options.go	Introduces DiscoveryTagKey, binds --discovery-tag-key, and validates it to prevent KQL injection.
tools/grafanactl/cmd/base/options_test.go	Adds coverage to ensure invalid tag keys are rejected.
pipelines/types/pipeline.schema.v1.json	Adds discoveryTagKey fields to Grafana step schemas.
pipelines/types/common.go	Adds DiscoveryTagKey to Grafana pipeline step structs and required-input discovery.

Review details

• Files reviewed: 9/9 changed files
• Comments generated: 1
• Review effort level: Lite

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[Abby Duke (abiduke612)]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: abiduke612, rachelvweber

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