Fix buildslave offline alert text
Fix buildslave offline alert text

BUG=skia:3961
TBR=jcgregorio

Review URL: https://codereview.chromium.org/1677583002

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot