Update DAST report fixture, Fix deduplication logic

What does this MR do?

• Update DAST report fixtures to the latest format.
• Fixes a bug in deduplication where some vulnerabilities were being deduplicated incorrectly. (Details: WASC is a class of vulnerabilities, similar to CWE therefore multiple vulnerabilities (occurrences) can have the same WASC identifier)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Relevant to #13034 (closed) and #11930 (closed)