Upgrade Email-ext plugin to 2.38.1 (#345)

This PR will fix #345. With being able to also test saving the main config file now, a couple other updates were necessary, which have been missed by the Jenkins upgrade.
Oh, now I see.   Somehow this section (logRotator) existed twice in that patch. Not sure why. So this simply removes the additional copy, whereby the change from 10 to 200 happens before: https://github.com/whimboo/mozmill-ci/blob/emailext/config/production/jenkins.patch#L1589. So nothing has to be changed here.