Schema: convert dashboards from v1beta1 to v2beta1 (#109037)

- Implement full conversion pipeline from v1beta1 → v2beta1
- Ensure frontend–backend parity for all dashboard serialization paths
- Add automatic data loss detection for conversions (panels, queries, annotations, links, variables)
- Extract atomic conversion functions for v0 → v1beta1 → v2alpha1 → v2beta1
- Introduce conversion metrics and detailed logging for loss tracking
- Normalize datasource resolution, defaults, and annotation processing
- Improve panel layout serialization and y-coordinate normalization
- Fix inconsistencies in nested panels and collapsed row behavior
- Refine variable handling:
  - Filter refId from variable query specs
  - Default variable refresh to 'never' (matches frontend)
  - Fix constant and interval variable handling for missing queries
- Unify schema defaults (enable, hide, iconColor, editable, liveNow)
- Fix pluginId usage (UID vs type) and datasource references
- Fix metrics.go bug swallowing errors (return nil → return err)
- Add tests for version-specific conversion error handling
- Add data loss detection tests using source/target version comparison
- Clean up lint issues, legacy code, and redundant files
- Update OpenAPI snapshots and migrated dashboards
- Improve backend migrator to reuse datasource provider and match frontend logic

Co-authored-by: Haris Rozajac <haris.rozajac12@gmail.com>
Co-authored-by: Oscar Kilhed <oscar.kilhed@grafana.com>
Co-authored-by: Stephanie Hingtgen <stephanie.hingtgen@grafana.com>

apps/dashboard/pkg/migration/conversion/v2_test.go

@@ -0,0 +1,42 @@
+package conversion
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	dashv2alpha1 "github.com/grafana/grafana/apps/dashboard/pkg/apis/dashboard/v2alpha1"
+	dashv2beta1 "github.com/grafana/grafana/apps/dashboard/pkg/apis/dashboard/v2beta1"
+)
+
+// TestV2alpha1ConversionErrorHandling tests that v2alpha1 conversion functions properly handle errors
+func TestV2alpha1ConversionErrorHandling(t *testing.T) {
+	t.Run("Convert_V2alpha1_to_V2beta1 sets status correctly on success", func(t *testing.T) {
+		source := &dashv2alpha1.Dashboard{
+			ObjectMeta: metav1.ObjectMeta{
+				Namespace: "default",
+				Name:      "test-dashboard",
+			},
+			Spec: dashv2alpha1.DashboardSpec{
+				Title: "test dashboard",
+				Layout: dashv2alpha1.DashboardGridLayoutKindOrRowsLayoutKindOrAutoGridLayoutKindOrTabsLayoutKind{
+					GridLayoutKind: &dashv2alpha1.DashboardGridLayoutKind{
+						Kind: "GridLayout",
+						Spec: dashv2alpha1.DashboardGridLayoutSpec{},
+					},
+				},
+			},
+		}
+		target := &dashv2beta1.Dashboard{}
+
+		err := Convert_V2alpha1_to_V2beta1(source, target, nil)
+
+		require.NoError(t, err)
+		// Verify success status is set correctly
+		require.NotNil(t, target.Status.Conversion)
+		require.False(t, target.Status.Conversion.Failed)
+		require.Equal(t, dashv2alpha1.VERSION, *target.Status.Conversion.StoredVersion)
+		require.Nil(t, target.Status.Conversion.Error)
+	})
+}