Remove undefined from docs

What does this MR do?

Cleanup MR. We no longer have undefined confidence and severity levels. This MR rewords one sentence and removes two places where undefined confidence and severity level mentioned.

Related issues

#202685 (closed)

Author's checklist (required)

• Follow the Documentation Guidelines and Style Guide.
• If you have developer access or higher (for example, GitLab team members or Core Team members)
  • Assign the designated Technical Writer.

Review checklist

All reviewers can help ensure accuracy, clarity, completeness, and adherence to the Documentation Guidelines and Style Guide.

1. Primary Reviewer

• Review by a code reviewer or other selected colleague to confirm accuracy, clarity, and completeness. This can be skipped for minor fixes without substantive content changes. (skipping for minor change)

2. Technical Writer

• Optional: Technical writer review. If not requested for this MR, must be scheduled post-merge. To request for this MR, assign the writer listed for the applicable DevOps stage.
  • Add Technical Writing and docs:: workflow label.
  • Add docs-only when the only files changed are under doc/*.

3. Maintainer

1. Review by assigned maintainer, who can always request/require the above reviews. Maintainer's review can occur before or after a technical writer review.
2. Ensure a release milestone is set.
3. If there has not been a technical writer review, create an issue for one using the Doc Review template.