Move the init code to the relevant folder

What does this MR do?

In order to increase consistency across the app, moved the app init code under the vulnerabilities folder. We've been following this practice across all Security Dashboards, so this tiny refactor makes sure that we follow the same principles in the Vulnerabilities views as well.

Screenshots (strongly suggested)

Nothing changes visually, but to prove that visually it still works, here's the screenshot:

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

Related to #285084 (closed)