Adjust `EE::Projects::IssuesController` not to create a `Vulnerabilities::Feedback`

Implementation plan

Modify EE::Projects::IssuesController not to create a new feedback object, but only create a vulnerability.

• We will need to set the present_on_default_branch to false for the new vulnerabilities (if we need to create one)

similar to #368311 (closed)

Verification steps:

• Create an issue from Vulnerability details page
• Make sure it is creating issue link with FF enabled
• Make sure we are not creating Feedback in db