nci watcher jobs don't work when run by timer

[jriddell]

NCI watcher jobs work fine when run manually but when run on the nightly timer they fail e.g.
https://build.neon.kde.org/view/watcher/job/watcher_release_neon-packaging_vc/237/console
It complains that
/tooling/lib/pangea/mail.rb:36:in `fetch': key not found: "PANGEA_MAIL_CONFIG_PATH" (KeyError)

run manually:
https://build.neon.kde.org/view/watcher/job/watcher_release_neon-packaging_vc/238/console

[jriddell]

The credentials plugin should set the environment variable, it's set to do so in the job configuration.

maybe https://issues.jenkins-ci.org/browse/JENKINS-32402