The new metrics is:
cloudprovider_gce_api_request_duration_seconds{request, region, zone}
cloudprovider_gce_api_request_errors{request, region, zone}
`request` is the specific function that is used.
`region` is the target region (Will be "<n/a>" if not applicable)
`zone` is the target zone (Will be "<n/a>" if not applicable)
Note: this fixes some issues with the previous implementation of
metrics for disks:
- Time duration tracked was of the initial API call, not the entire
operation.
- Metrics label tuple would have resulted in many independent
histograms stored, one for each disk. (Did not aggregate well).
Each major interface is now in its own file. Any package private
functions that are only referenced by a particular module was also moved
to the corresponding file. All common helper functions were moved to
gce_util.go.
This change is a pure movement of code; no semantic changes were made.
