Fix: Handle float apiserver buckets

[SuperQ]

Depending on the version of client_golang and metrics format (Prometheus vs OpenMetrics), bucket names may contain either integer or float formatting.

Use a regexp match to select either format.

[SuperQ]

Ping @povilasv :)

[povilasv]

@SuperQ sorry for delay, given the

kubernetes-mixin/rules/kube_apiserver-config.libsonnet

Line 14 in dd5c59a

kubeApiserverWriteLatency: '1',

is configureable, can't you just configure differently?

I don't really undertand why we need regex here 🤔

[SuperQ]

A regexp is needed because different versions of K8s produce different le values depending on a few different factors. Since it's somewhat dynamic, using a regexp makes it compatible with different version. I suppose I could put the regexp changes into the default config.

[SuperQ]

Alternative implementation: #965

[skl]

Suggest we take #965 and close this one.