Remove email confirmation in group creation for onboarding

What does this MR do?

Remove email confirmation in group creation for onboarding

Related to #296507 (closed) and similar to !43683 (diffs)

Manual testing

1. Enable the feature flag soft_email_confirmation

Feature.enable(:soft_email_confirmation)

2. Enable gitlab.com like environment in /admin/application_settings/general

Check feature availability on namespace plan
Enabling this will only make licensed EE features available to projects if the project namespace's plan includes the feature or if the project is publi

3. Enable Send confirmation email on sign-up on admin/application_settings/general

Screenshots

Before	After

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• 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

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team