tabledesc: fix bug in unupgraded descriptor validation

In the haste of cockroachdb#57066 we erroneously checked the origin rather than reference
column ID when validating an inbound fk reference. The tests did not catch this
error because the column IDs were the same on both sides.

Release note (bug fix): Fix a bug related validation of unupgraded pre-19.2
inbound foreign keys.

pkg/sql/catalog/tabledesc/structured.go

@@ -1657,7 +1657,7 @@ func (desc *Immutable) validateCrossReferences(ctx context.Context, dg catalog.D
 					fk.Index, desc.Name, backref.Name, originTable.GetName(),
 				)
 			}
-			if originalReferencedIndex.IsValidReferencedIndex(backref.OriginColumnIDs) {
+			if originalReferencedIndex.IsValidReferencedIndex(backref.ReferencedColumnIDs) {
 				found = true
 			}
 			return nil

pkg/sql/catalog/tabledesc/structured_test.go

@@ -821,7 +821,7 @@ func TestValidateCrossTableReferences(t *testing.T) {
 				Indexes: []descpb.IndexDescriptor{
 					{
 						ID:        2,
-						ColumnIDs: []descpb.ColumnID{1},
+						ColumnIDs: []descpb.ColumnID{7},
 						Unique:    true,
 					},
 				},
@@ -831,7 +831,7 @@ func TestValidateCrossTableReferences(t *testing.T) {
 						ReferencedTableID:   51,
 						ReferencedColumnIDs: []descpb.ColumnID{1},
 						OriginTableID:       52,
-						OriginColumnIDs:     []descpb.ColumnID{1},
+						OriginColumnIDs:     []descpb.ColumnID{7},
 					},
 				},
 			},