This ticket is to make mongod recover on startup which database prefixes to block/reject operations for.

• Add a function void recoverTenantMigrationAccessBlockers(OperationContext* opCtx) to migrating_tenant_donor_util.cpp that scans config.migrationDonors (see example), and for each doc:
  • Creates a TenantMigrationAccessBlocker for that “databasePrefix” and add()'s it to TenantMigrationAccessBlockerByPrefix
  • If the doc has "blockTimestamp" set, call startBlockingWrites() and then startBlockingReadsAfter() with the “blockTimestamp” on the TenantMigrationAccessBlocker
  • If the doc's state is “commit” , also call commit() on the TenantMigrationAccessBlocker
  • If the doc's state is “abort” , also call abort() on the TenantMigrationAccessBlocker

• Call the new recoverTenantMigrationAccessBlockers function just before where prepared transactions are recovered on startup

This ticket should also test that the code works by restarting the donor

• while the migration is in the "blocking" state
• after the migration has committed
• after the migration has aborted

and confirming that the in-memory state was recovered correctly. See tenant_migration_donor_state_machine.js for an example of pausing a migration while it's blocking and checking the donor's in-memory state.