Add filtering for cluster agent in GraphQL Vulnerabilities API

What does this MR do and why?

In this MR we're adding ability to filter vulnerabilities by cluster agent which performed a cluster image scanning scan.

Database query

SELECT * FROM vulnerabilities INNER JOIN vulnerability_occurrences ON vulnerability_occurrences.vulnerability_id = vulnerabilities.id WHERE vulnerabilities.project_id = 27958807 AND vulnerability_occurrences.report_type = 7 AND (vulnerability_occurrences.location -> 'agent_id' ?| array['153813']);

Before: 2.497 s

 Nested Loop  (cost=1.00..2316.78 rows=1 width=1978) (actual time=2490.865..2490.868 rows=0 loops=1)
   Buffers: shared hit=2577 read=991 dirtied=147
   I/O Timings: read=2443.311 write=0.000
   ->  Index Scan using index_vulnerabilities_on_project_id_and_state_and_severity on public.vulnerabilities  (cost=0.56..703.56 rows=465 width=354) (actual time=6.515..1623.167 rows=736 loops=1)
         Index Cond: (vulnerabilities.project_id = 27958807)
         Buffers: shared hit=7 read=617 dirtied=147
         I/O Timings: read=1611.528 write=0.000
   ->  Index Scan using index_vulnerability_occurrences_on_vulnerability_id on public.vulnerability_occurrences  (cost=0.44..3.46 rows=1 width=1624) (actual time=1.175..1.175 rows=0 loops=736)
         Index Cond: (vulnerability_occurrences.vulnerability_id = vulnerabilities.id)
         Filter: ((vulnerability_occurrences.report_type = 7) AND ((vulnerability_occurrences.location -> 'agent_id'::text) ?| '{153813}'::text[]))
         Rows Removed by Filter: 1
         Buffers: shared hit=2570 read=374
         I/O Timings: read=831.783 write=0.000

After index is added: -> !76640 (merged)

After: 7.013 ms

 Nested Loop  (cost=7.94..67.26 rows=1 width=1978) (actual time=0.155..0.157 rows=0 loops=1)
   Buffers: shared hit=2
   I/O Timings: read=0.000 write=0.000
   ->  Bitmap Heap Scan on public.vulnerability_occurrences  (cost=7.50..25.76 rows=12 width=1624) (actual time=0.155..0.155 rows=0 loops=1)
         Buffers: shared hit=2
         I/O Timings: read=0.000 write=0.000
         ->  Bitmap Index Scan using index_vulnerability_occurrences_on_location_agent_id  (cost=0.00..7.50 rows=12 width=0) (actual time=0.100..0.101 rows=0 loops=1)
               Index Cond: ((vulnerability_occurrences.location -> 'agent_id'::text) ?| '{153813}'::text[])
               Buffers: shared hit=2
               I/O Timings: read=0.000 write=0.000
   ->  Index Scan using vulnerabilities_pkey on public.vulnerabilities  (cost=0.44..3.46 rows=1 width=354) (actual time=0.000..0.000 rows=0 loops=0)
         Index Cond: (vulnerabilities.id = vulnerability_occurrences.vulnerability_id)
         Filter: (vulnerabilities.project_id = 27958807)
         Rows Removed by Filter: 0
         I/O Timings: read=0.000 write=0.000

How to set up and validate locally

1. Create new project.
2. Create and configure your cluster and CI configuration to run Cluster Image Scanning (https://docs.gitlab.com/ee/user/application_security/cluster_image_scanning/).
3. In gitlab-ci.yml file add:

include:
  - template: Security/Cluster-Image-Scanning.gitlab-ci.yml

cluster_image_scanning:
  variables:
    CIS_ANALYZER_IMAGE: registry.gitlab.com/gitlab-org/security-products/analyzers/cluster-image-scanning:342662-read-cluster-agent-id
    CIS_CLUSTER_AGENT_IDENTIFIER: 46357

1. Run pipeline, verify if vulnerabilities were created.
2. Go to GraphQL Explorer and try to fetch vulnerabilities by clusterAgentId (using gid://gitlab/Clusters::Agent/46357)
3. You should see vulnerabilities in the response.
4. Try again with different clusterAgentId

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 #342662 (closed)