collator-protocol: Re-advertise collations when peer authority IDs are updated

[lexnv]

The collator protocol contained a race-condition which could manifest as "Collation wasn't advertised".

A given peer ("A") can connect before the new authority keys are received via UpdatedAuthorityIds (nk -- new key).

• T0: peer A connectsPeerConnected
• T1: peer A sends its current view PeerViewChange
  • Peer A wants the block N
• T2: validator_group.should_advertise_to: checks peer A for key nK (the new key)
  • We don't have this key stored and therefore return ShouldAdvertiseTo::NotAuthority
• T3: UpdatedAuthorityIds arrives with (peer A, [nK])

At this point, we have the collation, peer A wants to collation, we know peer A is an authority but we never send the collation back. Then, the collation will expire with "Collation wasn't advertised".

To close the gap, the UpdatedAuthorityIds events will trigger a re-advertisement of collations

• note: if the advertisement was already sent, the logic does not resend it (achieved in should_advertise_to).

Part of the stabilization of:

• [ElasticScaling] Enable ElasticScaling on AHKusama and AHPolkadot #10425

[paritytech-workflow-stopper]

All GitHub workflows were cancelled due to failure one of the required jobs.
Failed workflow url: https://github.com/paritytech/polkadot-sdk/actions/runs/21287736978
Failed job name: fmt

[lexnv]

/cmd prdoc --audience node_dev --bump patch

[alexggh]

Fix looks correct, but UpdatedAuthorityIds is not something we should receive that often, because the AuthorityIds usually change only around session boundary when you get new peers that you might not discover yet.

How often did this happen ?