Remove METADATA files from implicit dependencies of SBOMs

Bug: 377969922
Test: lunch aosp_cf_x86_64_phone-trunk_staging-eng && m sbom
Test: m nothing, remove a METADATA file and m sbom
Test: run "m sbom" 2+ times, and SBOM is re-generated in each build
Change-Id: I42e303a56187ab2a96c3d709fbf8f2f54d1d4ca7