refactor: standardize default a link styling

[BlairCurrey]

Changes proposed in this pull request

• renames tooltip css class to default-link
• applies to pre-existing a elements that used a different method to achieve default(ish) styling

Context

Suggestion for PR https://github.com/interledger/rafiki/pull/2716

Checklist

• [ ] Related issues linked using fixes #number
• [ ] Tests added/updated
• [ ] Documentation added
• [ ] Make sure that all checks pass
• [ ] Bruno collection updated