Resolve "Follow-up from "Resolve "API to get all project/group members returns duplicates"""

What does this MR do?

Changes MembersFinder in order to fetch access_level from projects_authorizations; if the associated record in projects_authorizations doesn't exists (for example when user is invited) falls-back to members.access_level.

This is needed in order to return the correct access_level on the project for the member.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance 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

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

Closes #62284 (closed) and also #62988 (closed)