test: make portable fixtures optional and cover xigmanas

internal/collector/redfishprofile/profile_inspur_group_oem_platforms_test.go

@@ -186,6 +186,9 @@ func loadRawExportTreeFromExampleZip(t *testing.T, name string) map[string]inter
 	path := filepath.Join("..", "..", "..", "example", name)
 	f, err := os.Open(path)
 	if err != nil {
+		if os.IsNotExist(err) {
+			t.Skipf("optional example zip %s is not present", path)
+		}
 		t.Fatalf("open example zip %s: %v", path, err)
 	}
 	defer f.Close()