Release v19.31.7

Fixed

• A full reducer replay now rebuilds the reducer's read model from the event log. Previously the replay completed without rewriting existing documents, so a changed reducer was never applied to read models already built. (#4335)
• A reducer replay in which any partition fails is abandoned rather than promoted, so the read model keeps its previous, complete state instead of being replaced by a partial rebuild. The failed partitions are recorded on the reducer as before.