Move to btn-confirm from btn-success in dashboard directory

What does this MR do?

Move to btn-confirm from btn-success in dashboard directory

As a part of https://gitlab.com/gitlab-com/marketing/community-relations/contributor-program/hackathon/-/issues/50

Does this MR meet the acceptance criteria?

Conformity

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• Documentation (if required)
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• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

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