Add buckets to gce_api_request_duration_seconds metric

[cezarygerard]

Define Buckets in gce_api_request_duration_seconds metric to cover latencies from 5ms to 5 minutes+

The default buckets: DefBuckets = []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10}
defined in, github.com/prometheus/client_golang/prometheus/histogram.go
do not cover long running requests, e.g. backend service update takes 30-40 seconds.

[k8s-ci-robot]

Hi @cezarygerard. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[cezarygerard]

/assign @swetharepakula

[swetharepakula]

/ok-to-test

[swetharepakula]

/approve
/lgtm

[swetharepakula]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cezarygerard, panslava, swetharepakula

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