ci_fairy: Include commit SHA in junit error

It is already included in the testsuite name, but that isn't shown
in gitlab's UI, with the result that the front-page error report
is often useless and the user has to check out the pipeline logs.

Signed-off-by: Florian Müllner <fmuellner@gnome.org>
4 jobs for master in 1 minute and 31 seconds (queued for 1 second)
Child pipeline (parent)
Status Job ID Name Coverage
  Bootstrapping
passed #7645201
aarch64
bootstrap@aarch64

00:01:31

passed #7645200
bootstrap@x86_64

00:00:59

 
  Bootstrapping Qemu
passed #7645203
kvm
bootstrap-qemu-mkosi@x86_64

00:00:14

passed #7645202
bootstrap-qemu@x86_64

00:00:14