deployment: sequencer selector labels

[idan-starkware]

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[cursor]

PR Summary

Medium Risk
Incorrect pod selectors can prevent rollouts or leave Services pointing at no endpoints; the change is small but directly affects which pods workloads manage.

Overview
Deployment and StatefulSet matchLabels now use app: sequencer and service: sequencer-<service name> instead of selecting pods with only the service value taken from the merged label map.

This makes workload selectors explicit and consistent per sequencer component (e.g. core vs committer) rather than relying on whatever service ended up on statefulset_labels.

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[reviewable-StarkWare]

This change is 

[ShahakShama]

@ShahakShama reviewed 2 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on idan-starkware).