libct: switch final WithProcfd users to WithProcfdFile

This probably should've been done as part of commit d40b3439a9
("rootfs: switch to fd-based handling of mountpoint targets") but it
seems I missed them when doing the rest of the conversions.

This also lets us remove utils.WithProcfd entirely, as well as
pathrs.MkdirAllInRoot. Unfortunately, WithProcfd was exposed in the
externally-importable "libcontainer/utils" package and so we need to
have a deprecation notice to remove it in runc 1.5.

Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>

internal/pathrs/mkdirall_pathrslite.go

@@ -87,13 +87,3 @@ func MkdirAllInRootOpen(root, unsafePath string, mode os.FileMode) (*os.File, er
 		return pathrs.MkdirAllHandle(rootDir, unsafePath, mode)
 	})
 }
-
-// MkdirAllInRoot is a wrapper around MkdirAllInRootOpen which closes the
-// returned handle, for callers that don't need to use it.
-func MkdirAllInRoot(root, unsafePath string, mode os.FileMode) error {
-	f, err := MkdirAllInRootOpen(root, unsafePath, mode)
-	if err == nil {
-		_ = f.Close()
-	}
-	return err
-}