Curriculum Inventory collects all available academic levels, rather than those referenced in the report

[saschaben]

When we generate the XML output, the section is pulling all available rows in the curriculum_inventory_academic_levels table, rather than just the levels referenced in sequence blocks in the report. This causes an error in the upload, as any level referenced in the XML Must have at least one sequence block associated with it.

While this could be addressed by limiting the data in the table, it would be better overall to have the XML generated properly.