Have python_moztelemetry use the Probe Info Service instead of mozilla-central parsers

[chutten]

Nobody likes server-side parsing. So we should let the Probe Info Service do it for us. Then we can delete all the vendored parsers!

[chutten]

@fbertsch, @robhudson, and I had a conversation about this today.

There were a couple of details that cropped up that make this interesting:

1. mozaggregator seems to be the only service that cares about parsing custom (ie, not tip of tree) definitions files. And it only does so in order to show probes in Beta that have been removed in Nightly, until that removal of the probe reaches Beta.
2. Adopting the Probe Info Service means no longer being sure whether a probe coming from a client was expired in that client's build (since probeinfo has revs which aren't comparable without a VCS setup). Maybe if we had buildids in the probeinfo we could compare.
3. We're not too concerned about the perf and size implications of aggregating the extra data coming in from older builds on channels whose definitions files have had probes removed. Probe owners are already bad for leaving expired probe definitions in place in perpetuity already.