Two things were done to optimize audit observer:
* monik call was removed as we have different way to track it
* no new allocation for audit.Segment struct inside observer
Benchmark against 'main':
name old time/op new time/op delta
RemoteSegment/Cockroach/multiple_segments-8 5.85µs ± 1% 0.74µs ± 4% -87.28% (p=0.008 n=5+5)
name old alloc/op new alloc/op delta
RemoteSegment/Cockroach/multiple_segments-8 2.72kB ± 0% 0.00kB ~ (p=0.079 n=4+5)
name old allocs/op new allocs/op delta
RemoteSegment/Cockroach/multiple_segments-8 50.0 ± 0% 0.0 -100.00% (p=0.008 n=5+5)
Change-Id: Ib973e48782bad4346eee1cd5aee77f0a50f69258
