Consolidated createOverlayFile and updateOverlayFile to addOverlayFile

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

internal/pkg/util/util.go

@@ -362,21 +362,6 @@ func AppendLines(fileName string, lines []string) error {
 	return nil
 }
 
-func OverwriteFile(fileName string, content []byte) error {
-	wwlog.Verbose("overwrite file %s", fileName)
-	file, err := os.OpenFile(fileName, os.O_RDWR|os.O_TRUNC, 0o644)
-	if err != nil {
-		return fmt.Errorf("failed to open file: %s, err: %w", fileName, err)
-	}
-	defer file.Close()
-
-	_, err = file.Write(content)
-	if err != nil {
-		return fmt.Errorf("while writing file: %s, err: %w", fileName, err)
-	}
-	return file.Sync()
-}
-
 /*
 ******************************************************************************
 

internal/pkg/util/util_test.go

@@ -92,19 +92,3 @@ func Test_FindFilterFiles(t *testing.T) {
 		})
 	}
 }
-
-func Test_Overwrite(t *testing.T) {
-	t.Run("overwrite a file", func(t *testing.T) {
-		env := testenv.New(t)
-		defer env.RemoveAll()
-		env.CreateFile("file")
-		env.WriteFile("file", "hello world")
-
-		assert.Equal(t, "hello world", env.ReadFile("file"))
-
-		err := OverwriteFile(env.GetPath("file"), []byte("hello warewulf"))
-		assert.NoError(t, err)
-
-		assert.Equal(t, "hello warewulf", env.ReadFile("file"))
-	})
-}