pkg/system: remove stubs for deprecated sequential functions

These functions were moved to github.com/moby/sys/sequential, and the
stubs were added in 509f19f611d9316960ae176cdf31c401aa9bcce3, which is
part of the 22.x release, so we can safely remove these from master.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

pkg/system/filesys_deprecated.go

@@ -1,35 +0,0 @@
-package system
-
-import (
-	"os"
-
-	"github.com/moby/sys/sequential"
-)
-
-// CreateSequential is deprecated.
-//
-// Deprecated: use os.Create or github.com/moby/sys/sequential.Create()
-func CreateSequential(name string) (*os.File, error) {
-	return sequential.Create(name)
-}
-
-// OpenSequential is deprecated.
-//
-// Deprecated: use os.Open or github.com/moby/sys/sequential.Open
-func OpenSequential(name string) (*os.File, error) {
-	return sequential.Open(name)
-}
-
-// OpenFileSequential is deprecated.
-//
-// Deprecated: use github.com/moby/sys/sequential.OpenFile()
-func OpenFileSequential(name string, flag int, perm os.FileMode) (*os.File, error) {
-	return sequential.OpenFile(name, flag, perm)
-}
-
-// TempFileSequential is deprecated.
-//
-// Deprecated: use os.CreateTemp or github.com/moby/sys/sequential.CreateTemp
-func TempFileSequential(dir, prefix string) (f *os.File, err error) {
-	return sequential.CreateTemp(dir, prefix)
-}