Explicitly make manual CI jobs non-blocking

What does this MR do?

When not using rules, when: manual had a default allow_failure: true associated with it. However, when using rules, when:manual has allow_failure: false associated with it. When we did the refactor in !4188 (merged), we missed this fact and this caused manual job to be blocking and end up causing #5748 (closed).

From https://docs.gitlab.com/ee/ci/yaml/#whenmanual

This MR changes situation regarding allow_failure to what it was before !4188 (merged) was merged.

Related issues

Closes: #5748 (closed)

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion

Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• Pipeline is green on dev.gitlab.org if the change is touching anything besides documentation or internal cookbooks
• trigger-package has a green pipeline running against latest commit

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for the GitLab Chart opened

Closes #5748 (closed)