feat: Do not auto-upgrade KeyPerf to RestPerf if RestPerf exists

[cgrinds]

No description provided.

[Copilot]

Pull request overview

This PR adds REST performance capability detection to remote cluster discovery and uses it to prevent automatically replacing RestPerf with KeyPerf on disaggregated systems when RestPerf is actually available.

Changes:

• Extend conf.Remote with a HasRESTPerf flag derived from a REST API probe.
• Add HrefBuilder.ReturnRecords() to allow disabling record returns for capability checks.
• Adjust collector upgrade logic and tests to preserve RestPerf when supported.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
pkg/conf/remotes.go	Adds HasRESTPerf to Remote and sets it during REST-based remote creation.
cmd/tools/rest/href_builder.go	Adds return_records configurability via a new builder option.
cmd/tools/rest/client.go	Probes api/cluster/counter/tables to populate HasRESTPerf during UpdateClusterInfo.
cmd/poller/poller.go	Updates upgrade logic to avoid RestPerf → KeyPerf when HasRESTPerf is true.
cmd/poller/poller_test.go	Adds test coverage for AFX/disaggregated behavior when HasRESTPerf is true.

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