Remove cron flags from ftl dev

[alecthomas]

They are very verbose:

      --cron-ftl-endpoint=http://127.0.0.1:8897
                                   Schema Service endpoint
                                   ($FTL_SCHEMA_ENDPOINT).
      --cron-timeline-endpoint=http://127.0.0.1:8894
                                   Timeline endpoint ($FTL_TIMELINE_ENDPOINT).
      --cron-raft-initial-members=CRON-RAFT-INITIAL-MEMBERS,...
                                   Initial members ($RAFT_INITIAL_MEMBERS)
      --cron-raft-initial-replica-ids=CRON-RAFT-INITIAL-REPLICA-IDS,...
                                   Initial replica IDs
                                   ($RAFT_INITIAL_REPLICA_IDS)
      --cron-raft-data-dir=STRING
                                   Data directory ($RAFT_DATA_DIR)
      --cron-raft-address=STRING
                                   Address to advertise to other nodes
                                   ($RAFT_ADDRESS)
      --cron-raft-listen-address=STRING
                                   Address to listen for incoming traffic.
                                   If empty, Address will be used
                                   ($RAFT_LISTEN_ADDRESS).
      --cron-raft-control-address=CRON-RAFT-CONTROL-ADDRESS
                                   Address to connect to the control server
                                   ($RAFT_CONTROL_ADDRESS)
      --cron-raft-shard-ready-timeout=5s
                                   Timeout for shard to be ready
      --cron-raft-retry-min=100ms
                                   Minimum retry interval
      --cron-raft-retry-max=10s    Maximum retry interval
      --cron-raft-retry-factor=2
                                   Factor to multiply the retry interval by
      --cron-raft-retry-jitter     Whether to add jitter to the retry interval
      --cron-raft-changes-interval=10ms
                                   Interval for changes to be checked
      --cron-raft-changes-timeout=1s
                                   Timeout for changes to be checked
      --cron-raft-query-timeout=5s
                                   Timeout for queries
      --cron-raft-rtt=200ms        Estimated average round trip time between
                                   nodes
      --cron-raft-election-rtt=10
                                   Election RTT as a multiple of RTT
      --cron-raft-heartbeat-rtt=1
                                   Heartbeat RTT as a multiple of RTT
      --cron-raft-snapshot-entries=100
                                   Snapshot entries
      --cron-raft-compaction-overhead=100
                                   Compaction overhead