apps: fix shared request state

proper fix for #424
I'm not sure i understand.

As a user i expect to see a timer for total message processing time, and when i do `--mode=multicast` i expect to see the timings it takes to send to all upstreams for each msg. The other stats are the times it takes for a single upstream. (To put another way the statusEvery n should only fire every that many messages, not that many upstream calls for the aggregate entry).

For multicast and round-robin it's 1:1 message to upstream call so there isn't a diff.