Allow user to delete a malformed tag in the UI

Problem

When a tag is malformed, it's not possible to delete it through the UI.

The reason why is discussed in this comment

"Looking at the backend I can confirm that the root cause for the UI issue you're seeing is #232815 (closed).

Regardless of the "invalid" message on the UI, nothing should stop us from deleting this tag through the UI/API. A tag delete request against the registry will definitely succeed.

So I think we can do the following:

1. If a tag is deemed as invalid (for whatever reason), we should not gray out the delete option for that tag in the UI;
2. When deleting a tag (either through the UI or API), the backend (Rails) should not halt if unable to fetch/validate the underlying image manifest. It should handle such exceptions gracefully and call the container registry tag delete endpoint."

Scope of this issue

Malformed tags should have the same delete behavior as a non-malformed tag:

• Trash icon is not greyed out
• Confirmation modal
• Delete succeeds