Add total number of SQL and Redis calls

[jgaskins]

In MethodProfiler, both duration and calls are tracked, but only duration is reported.

Based on the fact that WebCollector uses PrometheusExporter::Metric::Base.default_aggregation, which is a Summary, I imagine this was accidentally omitted based on a misunderstanding that the *_count metric would contain the value of calls. Instead, the middleware pre-aggregates durations for the request, so the *_count metrics only increment by 1 and AFAICT the calls value is never used.

This PR reports the calls value.