Refactor total builds metrics
* Remove `_total` from metric name, this is a gauge. * Split `running` and `created` builds into separate metrics. * Add `namespace.path` as new metric label. * Refactor `metrics_total` function to support new metrics and labeling. * Reduce cardinality for `pending` and `created` builds by ignoring values less than 10. * Split stale builds metrics to separate function. * Update specs.