Download file index cleanup deletes packaging indexes that should be retained

As part of !67 (merged), we added a task that deletes junk records from the download_file_index table. The initially stated query seems to be a little too broad though, and some of the installer and packaging index nodes are also getting cleaned up when they should be retained just in case.

To avoid loss of data, we've worked with @chills2023 to fix the data on production and have disabled the task on production in the meantime.