devserver metrics: fix a metric name issue

This CL fixes a wrong metric name.

BUG=None
TEST=None

Change-Id: Id65ebdc3f0c2b7cccc5407c44a0a501b0738e256
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/1823360
Reviewed-by: Congbin Guo <[email protected]>
Commit-Queue: Congbin Guo <[email protected]>
Tested-by: Congbin Guo <[email protected]>
Auto-Submit: Congbin Guo <[email protected]>
1 file changed