Remove "other role" details during signup

What does this MR do and why?

Introduce again the reverted MR due to broken master by fixing the feature spec in the merged pipeline due to several reverts occurring on the same files.

Remove "other role" details during signup

• remove the feature flag
• ignore the column

Original !45635 (merged) Revert #364295 (closed)

Issue https://gitlab.com/gitlab-org/growth/team-tasks/-/issues/282

Screenshots or screen recordings

See !45635 (merged) for original screen recording

How to set up and validate locally

On SaaS environment, you shouldn't be able to set a feature flag and see "other role" while registering a new user.

MR acceptance checklist

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