fix: Vuln tracking feature flag must be distinct from licensed feature

What does this MR do?

Renaming feature flag introduced in !54608 (merged) from vulnerability_finding_signatures to vulnerability_finding_tracking_signatures to avoid name collision with licensed feature.

Relates to #322044 (closed)

Does this MR meet the acceptance criteria?

Conformity

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• Separation of EE specific content

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Security

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