`rmi -f` inconsistent with docker

### Description

`TestRemoveRunningImage` comments are outlining the issue.

`rmi -f` an image with a running container will fail with nerdctl, while it will succeed with docker (and untag the image).

### Steps to reproduce the issue

na

### Describe the results you received and expected

na

### What version of nerdctl are you using?

main

### Are you using a variant of nerdctl? (e.g., Rancher Desktop)

None

### Host information

_No response_