Prevent delete volumes used by VMs

[nesitor]

Fix: Prevent a store message forget to be executed if the file is already used on a VM.

Related Clickup or Jira tickets : ALEPH-XXX

Self proofreading checklist

• Is my code clear enough and well documented
• Are my files well typed
• New translations have been added or updated if new strings have been introduced in the frontend
• Database migrations file are included
• Are there enough tests
• Documentation has been included (for new feature)

Changes

Fix: Prevent a store message forget to be executed if the file is already used on a VM.

How to test

Try to forget a volume that is used by a program or an instance. The forget should be blocked and the API should answer an error.