Stop adopting masters with machine API

Master machine assets were introduced by openshift#491 to adopt instances generated by tf. There was never a follow up to leverage adoption for fatrther addon features. Unless there's a good reason to keep the adoption, this PR removes the machine API master awareness and assets generation

pkg/asset/machines/master.go

@@ -201,12 +201,11 @@ func (m *Master) Generate(dependencies asset.Parents) error {
 
 // Files returns the files generated by the asset.
 func (m *Master) Files() []*asset.File {
-	files := make([]*asset.File, 0, 1+len(m.MachineConfigFiles)+len(m.MachineFiles))
+	files := make([]*asset.File, 0, 1+len(m.MachineConfigFiles))
 	if m.UserDataFile != nil {
 		files = append(files, m.UserDataFile)
 	}
 	files = append(files, m.MachineConfigFiles...)
-	files = append(files, m.MachineFiles...)
 	return files
 }
 
@@ -226,12 +225,6 @@ func (m *Master) Load(f asset.FileFetcher) (found bool, err error) {
 		return true, err
 	}
 
-	fileList, err := f.FetchByPattern(filepath.Join(directory, masterMachineFileNamePattern))
-	if err != nil {
-		return true, err
-	}
-
-	m.MachineFiles = fileList
 	return true, nil
 }