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

@@ -35,6 +35,8 @@ func Test_detectConfirm_confirm(t *testing.T) {
 	err = os.MkdirAll(javaDir, 0700)
 	require.NoError(t, err)
 
+	t.Chdir(dir)
+
 	tests := []struct {
 		name         string
 		detection    []appdetect.Project