display legend of doughnut only when graph is present

3 jobs for 135-comparison-no-data in 3 minutes and 33 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Build
passed #72879
k8s
build-backend

00:02:06

passed #72880
k8s
build-frontend

00:01:25

 
  Test
passed #72881
test-backend

00:01:27

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