Deprecate AnnounceAccounts

[saketh-are]

AnnounceAccounts is a legacy mechanism supporting Validator AccountId -> PeerId lookups. It was superseded by AccountsData about a year ago and has been awaiting deprecation:

nearcore/chain/network/src/peer_manager/network_state/mod.rs

Lines 596 to 606 in 7c0b58f

	// Find the target peer_id:
	// - first look it up in self.accounts_data
	// - if missing, fall back to lookup in self.graph.routing_table
	// We want to deprecate self.graph.routing_table.account_owner in the next release.
	let target = if let Some(peer_id) = peer_id_from_account_data {
	metrics::ACCOUNT_TO_PEER_LOOKUPS.with_label_values(&["AccountData"]).inc();
	peer_id
	} else if let Some(peer_id) = self.account_announcements.get_account_owner(account_id) {
	metrics::ACCOUNT_TO_PEER_LOOKUPS.with_label_values(&["AnnounceAccount"]).inc();
	peer_id
	} else {

By inspecting the ACCOUNT_TO_PEER_LOOKUPS metric for several mainnet validators, I've confirmed that AnnounceAccounts is no longer of use. Additionally, enough release versions have passed since the introduction of AccountsData that we can get rid of AnnounceAccounts entirely at this point (see #8182).

This PR removes all of the client code which has to do with creation and usage of AnnounceAccounts. I plan to send separate PRs removing related fields/types from the network message protocol and deprecating DBCol::AccountAnnouncements (as this PR is large enough already).

[VanBarbascu]

[nagisa]

I've confirmed that AccountsData is no longer of use.

Did you mean “AnnounceAccounts is no longer of use”?

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Seems quite nice otherwise!

[saketh-are]

I've confirmed that AccountsData is no longer of use.

Did you mean “AnnounceAccounts is no longer of use”?

Thanks, yes, updated.

[nagisa]

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