Use VulnerabilityReadsFinder for InstanceSecurityDashboard counts

What does this MR do and why?

Use VulnerabilityReadsFinder when retrieving counts for the instance security dashboard. This is more performant as vulnerability_reads is optimized for reading and can scan only one table. Additionally, VulnerabilitiesFinder has a bug where it clears previous scopes when filtering by state, as it overwrites @vulnerabilities with vulnerable.vulnerability_reads, which does not have the previously applied scopes.

Relates to: #435064 (closed)

SQL Queries

Before: https://console.postgres.ai/shared/7f6cf21b-d73b-4ce8-b0c8-3e2c99807f67

SELECT
    count(*) AS count_all,
    vulnerability_reads.severity AS vulnerability_reads_severity
FROM
    vulnerability_reads
    JOIN projects ON projects.id = vulnerability_reads.project_id
WHERE
    projects.archived = false AND
    vulnerability_reads.project_id IN (
        SELECT
            projects.id
        FROM
            projects
            LEFT JOIN project_features ON projects.id = project_features.project_id
        WHERE
            projects.id IN (
                SELECT
                    users_security_dashboard_projects.project_id
                FROM
                    users_security_dashboard_projects
                WHERE
                    users_security_dashboard_projects.user_id = 8953999
            ) AND
            (
                project_features.security_and_compliance_access_level > 0 OR
                project_features.security_and_compliance_access_level IS NULL
            )
    ) AND
    vulnerability_reads.state IN ( 1, 4 )
GROUP BY
    vulnerability_reads.severity
ORDER BY
    vulnerability_reads.severity DESC;

After: (now has report_type) https://console.postgres.ai/shared/4d746ac6-0920-43e1-9ad8-cb6688ab27b7

SELECT
    count(*) AS count_all,
    vulnerability_reads.severity AS vulnerability_reads_severity
FROM
    vulnerability_reads
    JOIN projects ON projects.id = vulnerability_reads.project_id
WHERE
    projects.archived = false AND
    vulnerability_reads.project_id IN (
        SELECT
            projects.id
        FROM
            projects
            LEFT JOIN project_features ON projects.id = project_features.project_id
        WHERE
            projects.id IN (
                SELECT
                    users_security_dashboard_projects.project_id
                FROM
                    users_security_dashboard_projects
                WHERE
                    users_security_dashboard_projects.user_id = 8953999
            ) AND
            (
                project_features.security_and_compliance_access_level > 0 OR
                project_features.security_and_compliance_access_level IS NULL
            )
    ) AND
    vulnerability_reads.report_type = 7 AND
    vulnerability_reads.state IN ( 1, 4 )
GROUP BY
    vulnerability_reads.severity
ORDER BY
    vulnerability_reads.severity DESC;

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Add projects with vulnerabilities to the security center (Note: You can seed a project with vulnerabilities)
2. Go to <gdk_url>/-/security/vulnerabilities
3. Operational vulnerability count should be 0.

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.