Unify Import verifier usage across parachain template and omninode.

[skunert]

In omni node we use the standard aura verifier and add it to a compatibility layer to allow old blocks with relay-chain consensus to be imported:

polkadot-sdk/cumulus/polkadot-omni-node/lib/src/nodes/aura.rs

Line 123 in 721f6d9

let aura_verifier = cumulus_client_consensus_aura::build_verifier::<

In the parachain template we use a verifier that does some extra equivocation checks:

polkadot-sdk/templates/parachain/node/src/service.rs

Line 151 in 721f6d9

cumulus_client_consensus_aura::equivocation_import_queue::fully_verifying_import_queue::<

It checks that no more than EQUIVOCATION_LIMIT blocks are imported at the same slot.

Having the equivocation check is desirable, we should also use this one in the omni-node.