Extend the use of `security_findings`
## Why are we doing this work
Currently, we are using the JSON report artifacts to create HTTP responses and ingest the vulnerabilities for the security dashboard. This requires us to download & parse the report artifacts whenever we need to use the report findings which is both a slow and resource-consuming operation.
We've already started using the `security_findings` table to store some meta-information about the report findings to prevent downloading & parsing all the artifacts always. The idea was, identifying which artifact(s) to download by using the `security_findings` table to reduce the resource consumption and speeding up the tasks.
As the next step, we can store the finding information in a JSONB column in the `security_findings` table to prevent using the report artifacts completely.
## Requirements
1. Report information submitted to sisense must continue to use raw data (https://gitlab.com/groups/gitlab-org/-/epics/8341#note_1016978180)
2. Finders date updated to read from the DB rather than JSON artifacts
3. As above, for API endpoints
epic