unittests: Fixes hostutil.GetFileType for Windows

GetFileType is meant to return the type of the given file by using os.Stat.
However, os.Stat doesn't work on Windows for Unix Sockets, causing an error to occur:

[2-Socket Test] unexpected error :
CreateFile C:\Users\Administrator\AppData\Local\Temp\test-get-filetype-2776877299\mt.sock:
The file cannot be accessed by the system.

This is a known issue and we're already using a workaround for this in
pkg/kubelet/util/util_windows.go.

This commit fixes this issue for GetFileType on Windows.

pkg/kubelet/util/util_unix.go

@@ -136,18 +136,6 @@ func LocalEndpoint(path, file string) (string, error) {
 	return filepath.Join(u.String(), file+".sock"), nil
 }
 
-// IsUnixDomainSocket returns whether a given file is a AF_UNIX socket file
-func IsUnixDomainSocket(filePath string) (bool, error) {
-	fi, err := os.Stat(filePath)
-	if err != nil {
-		return false, fmt.Errorf("stat file %s failed: %v", filePath, err)
-	}
-	if fi.Mode()&os.ModeSocket == 0 {
-		return false, nil
-	}
-	return true, nil
-}
-
 // NormalizePath is a no-op for Linux for now
 func NormalizePath(path string) string {
 	return path