Resolve vulnerability cross join issues in Sbom::DependenciesFinder

Problem to solve

All cross-joins arising from decomposing gitlab_sec from gitlab_main should be resolved. See parent epic for context.

1. Remove allowed cross-join for relevant relation using associated documentation for guidance on removing cross-joins or cross-transactions occurrences

In the case of DependenciesFinder, we allow-listed cross-transactions (example). We should resolve these by batching project fetching to avoid a cross-DB join.