Standardized posix time calculation which should fix negative latencies
being returned by benchmark when timezone was mismatched

Also included further breakdown of narwhal latencies ([investigation
notes](https://www.notion.so/mystenlabs/End2End-Latency-Investigation-027092e6dbd84aaa9784d502a8cd4d6a))
and updated local benchmark parameters, which is used in CI, to match
what we are currently using in production.

```
-----------------------------------------
 SUMMARY:
-----------------------------------------
 + CONFIG:
 Faults: 0 node(s)
 Committee size: 4 node(s)
 Worker(s) per node: 1 worker(s)
 Collocate primary and workers: True
 Input rate: 200 tx/s
 Transaction size: 512 B
 Execution time: 60 s

 Header number of batches threshold: 1 digests
 Header maximum number of batches: 1,000 digests
 Max header delay: 2,000 ms
 GC depth: 50 round(s)
 Sync retry delay: 10,000 ms
 Sync retry nodes: 3 node(s)
 batch size: 500,000 B
 Max batch delay: 200 ms
 Max concurrent requests: 500,000 

 + RESULTS:
 Batch creation latency: 179 ms
 Header creation latency: 462 ms
        Batch to header latency: 231 ms
 Certificate creation latency: 13 ms
        Request vote outbound latency: 6 ms
 Certificate commit latency: 460 ms

 Consensus TPS: 159 tx/s
 Consensus BPS: 81,616 B/s
 Consensus latency: 472 ms

 End-to-end TPS: 159 tx/s
 End-to-end BPS: 81,414 B/s
 End-to-end latency: 604 ms
-----------------------------------------
```