Fix DB Connections Flexible Identifiers not working with `requires_username` & `validation` options

[developerkunal]

🔧 Changes

• Fix for DB Connections Flexible Identifiers Compatibility: Adjusted the functionality to address the issue where Flexible Identifiers were not working correctly with requires_username and validation options. To use Flexible Identifiers, these attributes need to be removed from the configuration since they are not supported when using the attributes attribute.

📚 References

• Auth0 Management Update Connection

  📝 Checklist

  • [x] All new/changed/fixed functionality is covered by tests (or N/A)
  • [x] I have added documentation for all new/changed functionality (or N/A)

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 9.09091% with 10 lines in your changes missing coverage. Please review.

Project coverage is 84.31%. Comparing base (95bb953) to head (8f6c128).

Files	Patch %	Lines
src/tools/auth0/handlers/databases.ts	9.09%	4 Missing and 6 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #937 +/- ## ========================================== - Coverage 84.53% 84.31% -0.22% ========================================== Files 116 116 Lines 3776 3787 +11 Branches 737 743 +6 ========================================== + Hits 3192 3193 +1 - Misses 324 328 +4 - Partials 260 266 +6 ```

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