fix: stale canton console error

[jarekr-da]

This provides a build fix and instructions how to fix error with app-synchronizer feature flag

multi-sync-startup  | /app/app-synchronizer.sc:48: value EnableMultiSynchronizer is not a member of object com.digitalasset.canton.topology.transaction.SynchronizerTrustCertificate.ParticipantTopologyFeatureFlag
multi-sync-startup  |   Seq(SynchronizerTrustCertificate.ParticipantTopologyFeatureFlag.EnableMultiSynchronizer)
multi-sync-startup  |                                                                   ^

You can just take the start-localnet.ts fix (although it will slow down the build)