ChromeOS still has a few builds which generate email notifications via cbuildbot. If we can get rid of that, we can delete chromite code, stop deploying email credentials to builders, and stop uploading "streak" counter information to GS.

LUCI NOtify now allows notification emails to be set via the LUCI Build config, extra parameters in the build request (used for tryjobs), and via properties set during the build.

The later is new, and would enable this cleanup. Originally, I thought this would need to wait until we were autogenerating large numbers of LUCI Build configs.

https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/1370610