[plot] Assume a figure can contain multiple axes

For example a twin axis
4 jobs for twin-legend in 8 minutes and 26 seconds (queued for 6 seconds)
Status Name Job ID Coverage
  Build
passed build_linux_37 #229829
docker

00:04:24

80.0%
passed build_linux_38 #229830
docker

00:04:25

81.0%
passed build_macos_intel_37 #229827
macos intel

00:08:25

80.0%
passed build_macos_intel_38 #229828
macos intel

00:08:20

81.0%