tracker-controller: Label unit of timing measurements

Otherwise, it's not clear if these are timings or some kind of ID
number.

!147
2 jobs for master in 14 minutes and 40 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #891821
flatpak
flatpak

00:13:27

 
  Deploy
passed #891822
nightly

00:01:13