Incoming request stats are somewhat confusing

[bryancall]

We have proxy.process.http.incoming_requests and proxy.process.https.incoming_requests. However, http is all requests and https is just the requests that are TLS. Maybe rename http to total or and add a stat for non-TLS.

Here is the current code:
https://github.com/apache/trafficserver/blame/4d12805948ce7eab939a4fce0ca922eaacec5c25/src/proxy/http/HttpTransact.cc#L1519

[bryancall]

We need to look at overhauling the metrics in the 11.0.0 release.