When a student submits a PDF for an assignment but then removes it again, the teacher can still see and grade that PDF.

The submitted PDF file gets deleted but the images generated from each page of the PDF are still there so the PDF is effectively still there from the teacher's point of view.

Edit:
Steps to reproduce

1. Create a course and enrol a student.
2. Create an assignment with file submission and file annotations enabled.
3. As a student, submit a pdf for the assignment.
4. Run the following query and note the ids associated to the file submission(should be of component type user)

   select * from mdl_files order by id desc

5. As an admin/teacher, go the assignment and submission and file annotation interface.
6. Run the query from #4 and note down the files created as part of triggering the annotation plugin(should be of componentn type assignfeedback_editpdf)
7. Note down the pdf and the associated image generated.
8. As a student delete the pdf and note it has been removed from view from both the students view and when viewing the grading interface as a teacher.
9. Rerun #4 and note the user specific file has been deleted
10. As a teacher, Go to the grading UI and note the pdf doesn't exist in the 'File Submissions' column and 'Annotate PDF' is empty.
11. Click the 'Grade' button and note the deleted file comes up for grading. The generated image still exists in the db. If you go to the location described in the contenthash you can still view the generated image.