> Isn't it datareporting.healthreport.uploadEnabled (still unlocked and visible in the "options" -> "privacy & security" panel) that controls the upload, and toolkit.telemetry.enabled is only about whenever something is collected or not?

I’m not actually sure – I’ve heard conflicting reports from Mozilla volunteers and employees in the past, but the general statement is that Beta, Dev, and Nightly contain tracking, and you opt into that when downloading, because the smallprint below the download button tells you that they will track you.