CandidateDescriptor: disable collator signature and collator id usage (#4665)
Collator id and collator signature do not serve any useful purpose.
Removing the signature check from runtime but keeping the checks in the
node until the runtime is upgraded.
TODO:
- [x] PRDoc
- [x] Add node feature for core index commitment enablement
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Signed-off-by: Andrei Sandu <[email protected]>