Cleanup legacy findings logic

What does this MR do?

This MR removes some legacy code related to old security dashboard based on findings data. Since we removed our feature flag and using only one dashboard, now we are taking stab to clean our codebase.

This MR only removes some part of the legacy code from ProjectsHelper and touches a bit frontend to rename a property called hasPipelineData to hasVulnerabilities since we removed the dependency of pipeline from our dashboards.

Related to #207448 (closed)

Screenshots

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