fix: Drop Sbom::Occurrence#visible_to scope to resolve occurrence->projects cross-join

What does this MR do and why?

Drop cross-join by removing Sbom::Occurrence#visible_to scope in favor of limiting Explore::DependenciesController to admins only.

This effectively drops the visible_to usage within the Sbom::DependenciesFinder which was only used when dependable.is_a?(Organization)

See FAQ on parent epic for details on sec-decomposition effort.

Relates to Resolve vulnerability cross join issues in Sbom... (#477112 - closed)

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Database review query plans

Before

Previous Sbom::Occurrence.visible_to scope

https://console.postgres.ai/gitlab/gitlab-production-main/sessions/32913/commands/101458

SELECT "sbom_occurrences".*
FROM "sbom_occurrences"
INNER JOIN "projects" ON "sbom_occurrences"."project_id" = "projects"."id"
INNER JOIN
    "projects" AS "projects_sbom_occurrences"
    ON "sbom_occurrences"."project_id" = "projects_sbom_occurrences"."id"
INNER JOIN
    "project_authorizations"
    ON "projects_sbom_occurrences"."id" = "project_authorizations"."project_id"
WHERE
    "projects"."organization_id" = 1645
    AND "projects"."archived" = FALSE
    AND "project_authorizations"."user_id" = 401232

After

Closes to #477112 (closed)