Candidates pending availability by ParaId. They form a chain starting from the latest
included head of the para.
Use a different prefix post-migration to v1, since the v0 PendingAvailability storage
would otherwise have the exact same prefix which could cause undefined behaviour when doing
the migration.
Candidates pending availability by
ParaId. They form a chain starting from the latest included head of the para. Use a different prefix post-migration to v1, since the v0PendingAvailabilitystorage would otherwise have the exact same prefix which could cause undefined behaviour when doing the migration.