Patch Dependency Export to be resillient against invalid record matches

There is a standing issue in which it has been determined that some process in GitLab is, very infrequently, orphaning sbom_occurrences records.

It has been determined that this can, in some situations, result in group dependency exports failing, as the lack of a valid project for the sbom_occurrence prevents the successful retrieval of the input_file_blob_path, resulting in an error and failed export.

Investigating the cause of the orphaned records will take an unknown amount of time, but for now we can perhaps make the export more resilient to this circumstance to still allow a successful export.

It would likely be ideal to log that this is occurring so that invalid data in the database does not continue to go unnoticed once this mitigation is applied.