.github: Disable debug output for image-changes

[pothos]

The "set -x" bash debug output is very noisy and one doesn't even see the actual output in this noise.

[krnowak]

I'm not sure about this one. I don't even remember if we print anything meaningful to the image changes job's standard output. I think that the report you want should be available as a zipped artifact to download.

[github-actions]

Build action triggered: https://github.com/flatcar/scripts/actions/runs/8698555442

[pothos]

I'm not sure about this one. I don't even remember if we print anything meaningful to the image changes job's standard output. I think that the report you want should be available as a zipped artifact to download.

Checked this, yes, the actual output is just a few error about not finding certain OEM content reports because they weren't built. The report is archived and not printed.