hst/container: remove cover

This was never useful, and is now completely replaced by regular FilesystemConfig being able to mount tmpfs.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/app/seal_linux.go

@@ -474,10 +474,6 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *hst.Co
 		}
 	}
 
-	for _, dest := range config.Container.Cover {
-		seal.container.Tmpfs(dest, 1<<13, 0755)
-	}
-
 	// mount root read-only as the final setup Op
 	seal.container.Remount("/", syscall.MS_RDONLY)