Fix trigger_error() in legacy Update Manager deprecations to use __FUNCTION__

Pretty straightforward

Thanks! I probably should have credited you for this issue in the first place, since you pointed out the same problem with the initial MR I put up at 📌 Finish deprecating 'Update Manager' related code in Update Status Active . So even though that review normally wouldn't qualify for issue credit, you were the inspiration for me noticing this bug and fixing it. Therefore, saving credit for both of us.

Committed to 11.x - thanks!

larowlan → closed merge request !12071