bundle controller shard filtering based on cluster changes

[johnjcool]

Refers to #4484

This PR updates shard filtering behavior for cluster->bundle fan-out in internal/cmd/controller/reconciler/bundle_controller.go. When a fleet.Cluster changes (labels/annotations/spec/status), the controller now only enqueues reconcile requests for fleet.Bundle objects that should be processed by the current shard (ShardID), preventing cross-shard reconciles triggered by cluster updates.

[Copilot]

Pull request overview

This PR adds shard filtering to prevent cross-shard reconciliations in the bundle controller. When cluster objects change, the controller now only enqueues bundles that belong to the current shard, improving efficiency in multi-shard deployments.

Changes:

• Added shard filtering predicates to all watch handlers (Bundle, BundleDeployment, Cluster, Secret, ConfigMap)
• Removed global WithEventFilter in favor of per-watch filtering
• Ensured fan-out operations respect shard boundaries

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[weyfonk]

Thanks @johnjcool for your contribution :)
We like the idea, and need to figure out how far we want to take this.
For instance, recently-added monitoring of user-created secrets and config maps should also be impacted by this, yet we may not want to require users to add fleet.cattle.io/shard-ref labels to such resources.

[weyfonk]

Thanks @johnjcool for your contribution :) We like the idea, and need to figure out how far we want to take this. For instance, recently-added monitoring of user-created secrets and config maps should also be impacted by this, yet we may not want to require users to add fleet.cattle.io/shard-ref labels to such resources.

We've had a closer look, leading to the following conclusions:

• Sharding predicates (sharding.FilterByShardID(r.ShardID)) are not necessary against monitored secrets and config maps, because the logic mapping config maps and secrets to bundles monitoring them already takes care of filtering out bundles living in different shards
• Schedules were also affected by this mismatch; see Refine conditions for reconciles from cluster updates across shards #4730 for more details (@johnjcool , feel free to take a look, your comments are most welcome there too).

[weyfonk]

Superseded by #4730.
Thanks for this initiative :)