Dangerfile: update "throughput" to "worktype"

What does this MR do?

Update Dangerfile "throughput" language to "work type", per changes from gitlab-com/www-gitlab-com!75933 (merged)

Now "Work Type Classification" from https://about.gitlab.com/handbook/engineering/metrics/#work-type-classification

Checklist

See Definition of done.

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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

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 omnibus-gitlab opened