Block Propagation continues after TTD was hit

[jflo]

During mainnet-shadowfork-3, all Besu nodes seemed to continue accepting blocks over gossip from the main network, and saving them for later. This worked correctly in previous shadow forks, so is likely a regression.

2022-05-05 10:48:36.626+00:00 | vert.x-worker-thread-0 | INFO  | EngineForkchoiceUpdated | Consensus fork-choice-update: head: 0xc0b4b206cdd4be1311605e278878a3c1e21358ac71ece07fbd8f145c02814766, finalized: 0x0000000000000000000000000000000000000000000000000000000000000000
2022-05-05 10:48:45.261+00:00 | vert.x-eventloop-thread-6 | INFO  | EthStatsService | Connected to ethstats server
2022-05-05 10:48:45.815+00:00 | nioEventLoopGroup-3-2 | INFO  | RlpxAgent | comparing timestamps 1651747725815 with 1651747216614
2022-05-05 10:48:48.080+00:00 | nioEventLoopGroup-3-7 | INFO  | BlockPropagationManager | Saving announced block 14716823 (0x5128747f398aca50cca2cc43a7fec4478bdd209f6d279decf7466d77b09e9380) for future import

Here you can see block 14716823 being saved despite switching to proof of stake at block 14716821