No More Expired Probes, please!

[Chris H-C]

Hello, dev-platform and firefox-dev!

  Leaving expired Legacy Telemetry Histograms, Scalars, or Events in mozilla-central will now, as of bug 1918242[1] result in a test failure. Keeping the tree clean of expired probe definitions saves cycles, code size, and runtime memory.

  Many thanks to Florian Quèze for removing the remaining expired probes from the tree, allowing this test to land cleanly.

  If you have any questions, please reach via #telemetry:mozilla.org[2] or in reply to this email, and we'll be happy to help you out.

:chutten

[1]: https://bugzilla.mozilla.org/show_bug.cgi?id=1918242

[2]: https://chat.mozilla.org/#/room/#telemetry:mozilla.org