RHINENG-2867: fix store to advisory metadata and system advisories when update does not have an erratum

[psegedy]

When vmaas (or yum_updates) reports an update without erratum, then this erratum is returned as '' by getReportedAdvisories and in turn getAdvisoriesFromDB creates empty AdvisoryMetadata{} due to an issue with slice initialization. Empty AdvisoryMetadata has ID: 0 which cannot be stored to system_advisories since advisory with id=0 does not exist in advisory_metadata table.

2023/11/06 16:26:10 /go/src/app/evaluator/evaluate_advisories.go:149
[0.916ms] [rows:0] SELECT id, name FROM "advisory_metadata" WHERE name IN ('')
{"@timestamp":"2023-11-06T16:26:10.118Z","installable":1,"inventoryID":"b46d27c1-a747-4638-8c3a-1362bd5efa22","level":"info","message":"installable advisories"}

2023/11/06 16:26:10 /go/src/app/base/database/batch.go:72 ERROR: insert or update on table "system_advisories_24" violates foreign key constraint "advisory_metadata_id" (SQLSTATE 23503)
[1.183ms] [rows:-] INSERT INTO "system_advisories" ("advisory_id", "first_reported", "rh_account_id", "status_id", "system_id") VALUES (0, NULL, 1, 0, 4200239) ON CONFLICT (rh_account_id, system_id, advisory_id) DO UPDATE SET status_id = excluded.status_id RETURNING *
{"@timestamp":"2023-11-06T16:26:10.124Z","err":"unable to evaluate in database: evaluation with vmaas failed: Unable to evaluate and store results: Advisory analysis failed: Unable to store advisory data: Unable to update system advisories: ERROR: insert or update on table \"system_advisories_24\" violates foreign key constraint \"advisory_metadata_id\" (SQLSTATE 23503)","evalLabel":"upload","inventoryID":"b46d27c1-a747-4638-8c3a-1362bd5efa22","level":"error","message":"Eval message handling"}

Secure Coding Practices Checklist GitHub Link

• https://github.com/RedHatInsights/secure-coding-checklist

Secure Coding Checklist

• Input Validation
• Output Encoding
• Authentication and Password Management
• Session Management
• Access Control
• Cryptographic Practices
• Error Handling and Logging
• Data Protection
• Communication Security
• System Configuration
• Database Security
• File Management
• Memory Management
• General Coding Practices

[jira-linking]

Referenced Jiras:
https://issues.redhat.com/browse/RHINENG-2867