Revert "Alerting: Remove vendored models in migration service" (#76387)

Revert "Alerting: Remove vendored models in migration service (#74503)"

This reverts commit 6a8649d544.

pkg/services/sqlstore/migrations/ualert/datasource.go

@@ -0,0 +1,31 @@
+package ualert
+
+type dsUIDLookup map[[2]int64]string
+
+// GetUID fetch thes datasource UID based on orgID+datasourceID
+func (d dsUIDLookup) GetUID(orgID, datasourceID int64) string {
+	return d[[2]int64{orgID, datasourceID}]
+}
+
+// slurpDSIDs returns a map of [orgID, dataSourceId] -> UID.
+func (m *migration) slurpDSIDs() (dsUIDLookup, error) {
+	dsIDs := []struct {
+		OrgID int64  `xorm:"org_id"`
+		ID    int64  `xorm:"id"`
+		UID   string `xorm:"uid"`
+	}{}
+
+	err := m.sess.SQL(`SELECT org_id, id, uid FROM data_source`).Find(&dsIDs)
+
+	if err != nil {
+		return nil, err
+	}
+
+	idToUID := make(dsUIDLookup, len(dsIDs))
+
+	for _, ds := range dsIDs {
+		idToUID[[2]int64{ds.OrgID, ds.ID}] = ds.UID
+	}
+
+	return idToUID, nil
+}