Fix indentation of devops nudger job message

What does this MR do and why?

Follow-up of !2001 (diffs, comment 1291373680) to fix the indentation devops nudger job message.

This should fix comments like gitlab-org/gitlab#393162 (comment 1291328735):

Not sure how test this so I added puts missing_devops_labels_comment_request_body to spec/job/devops_labels_nudger_job_spec.rb to inspect:

Before	After

Expected impact & dry-runs

These are strongly recommended to assist reviewers and reduce the time to merge your change.

See https://gitlab.com/gitlab-org/quality/triage-ops/-/tree/master/doc/scheduled#testing-with-a-dry-run on how to perform dry-runs for new policies.

See https://gitlab.com/gitlab-org/quality/triage-ops/-/blob/master/doc/reactive/best_practices.md#use-the-sandbox-to-test-new-processors on how to make sure a new processor can be tested.

Action items

• If adding environment variables for reactive processors, update config/triage-web.yaml and .gitlab/ci/triage-web.yml
• (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable) Identify the affected groups and how to communicate to them:
  • /cc @person_or_group =>
  • Relevant Slack channels =>
  • Engineering week-in-review