Fix Gitaly duration timings of BlobService RPCs
For many Gitaly RPCs, previously the gitaly_duration_s
log timings
only accounted for the initial request/response time. We now measure the
total time it takes to consume the streaming response for the following
RPCs:
- GetBlob
- GetLFSPointers
- GetBlobs
- GetNewLFSPointers
This came up in #222247 (closed).
Part of #30334 (closed)
Edited by Sean Carroll