backstage release v2.92.0-rc.6

(plans) Hive merges Plans, Roadmap and the magazine in #2743 by @teemow
(gs) Show worker CPU and memory capacity of clusters in #2736 by @QuentinBisson

(repositories) Reach Create repository only from the Repositories page in #2741 by @marians

(scaffolder) Refresh cluster tokens when a template is submitted in #2735 by @QuentinBisson
(gs) Keep the sidebar without a main auth provider in #2742 by @teemow
(deps) Update dependency @bufbuild/protobuf to v2.15.0 in #2733 by @renovate[bot]
(backend) Warn at startup when the telemetry app ID is empty in #2746 by @teemow
(agent-platform) Read delete_cluster’s nothingLeft as removal done in #2753 by @teemow
(gs) Open the cluster page of a cluster a HelmRelease installs in #2754 by @teemow

Full Changelog: https://github.com/giantswarm/backstage/compare/v2.91.1...v2.92.0-rc.6