Fix Test_parseExecutableFiles CI failure

Replace ostest.Chdir (raw os.Chdir) with t.Chdir in
detect_confirm_test.go. The t.Chdir API integrates properly with Go
1.26's testing framework for process-wide cwd changes, preventing
subtle test state corruption that caused subsequent tests in the same
package to fail on CI.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: spboyer

cli/azd/internal/repository/detect_confirm_test.go

@@ -13,7 +13,6 @@ import (
 
 	"github.com/azure/azure-dev/cli/azd/internal/appdetect"
 	"github.com/azure/azure-dev/cli/azd/pkg/input"
-	"github.com/azure/azure-dev/cli/azd/test/ostest"
 	"github.com/stretchr/testify/require"
 )
 
@@ -35,7 +34,7 @@ func Test_detectConfirm_confirm(t *testing.T) {
 	err = os.MkdirAll(javaDir, 0700)
 	require.NoError(t, err)
 
-	ostest.Chdir(t, dir)
+	t.Chdir(dir)
 
 	tests := []struct {
 		name         string