Load project list only during loading the Security Dashboard

What does this MR do?

Related to #233017

This change improves the performance of loading next pages of Vulnerabilities in Group Security Dashboard by loading list of projects only once at the page load instead of reloading them every time user fetches new page. We have noticed that every time we fetch new page in Group Security Dashboard we are sending redundant request to fetch projects (even though they were loaded in the first query), this allows us to go down from 2.5s to 700ms to load next chunk of vulnerabilities.

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