Refactor upstream metrics code
What does this MR do and why?
The metrics provided by labkit are almost identical to the ones needed by Workhorse. The only different is timeToWriteHeaderDurationBuckets
Provided by labkit:
0.005, /* 5ms */
0.025, /* 25ms */
0.1, /* 100ms */
0.5, /* 500ms */
1.0, /* 1s */
10.0, /* 10s */
30.0, /* 30s */
Currently set by Workhorse, but likely just to reuse existing secondsDurationBuckets
0.005, /* 5ms */
0.025, /* 25ms */
0.1, /* 100ms */
0.5, /* 500ms */
1.0, /* 1s */
10.0, /* 10s */
30.0, /* 30s */
60.0, /* 30s */
300.0, /* 30s */