refactor(log): show merge request web url when it fails to assign a reviewer


this url may be useful for debugging and eventual fixing permission.
2 jobs for topic/default/log-mr-web-url in 29 seconds (queued for 26 seconds)
Status Job ID Name Coverage
  Lint
passed #62809
lint_black

00:00:29

passed #62810
lint_flake8

00:00:21