Work around Citoid bug in health check

The health check hits Citoid with an empty URL, which causes
it to output nothing. But hitting it with / works. This is
a bug in Citoid, but for now let's just hit the URL that works.

Change-Id: I48e4e0d8e9303a41e539e02ede3d6dbeda489860
Merge "Work around Citoid bug in health check" into production