Fetch only enabled reports

What does this MR do and why?

This MR fixes a bug where previously we fetched all reports regardless whether they were enabled or not. Now only enabled reports are fetched.

Screenshots or screen recordings

before	after

How to set up and validate locally

1. You'll need an EE License
2. You'll need to have runners enabled (See $2408961 for setting up a runner)
3. Enable :refactor_security_extension to turn this feature on.

echo "Feature.enable(:refactor_security_extension)" | rails c

1. Import https://gitlab.com/gitlab-examples/security/security-reports
2. Create a new MR by editing a file
3. Go to the MR page and check the widget

Note: you can enable or disable reports from Security & Compliance > Configuration on the side bar menu.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #374506 (closed)