Kill gorp (#19786)

* Kill gorp

Gorp is dead. Long live Gorp.

```release-note
NONE
```

testlib/helper.go

@@ -180,7 +180,7 @@ func (h *MainHelper) PreloadMigrations() {
 			panic(fmt.Errorf("cannot read file: %v", err))
 		}
 	}
-	handle := h.SQLStore.GetMaster()
+	handle := h.SQLStore.GetMasterX()
 	_, err = handle.Exec(string(buf))
 	if err != nil {
 		panic(errors.Wrap(err, "Error preloading migrations. Check if you have &multiStatements=true in your DSN if you are using MySQL. Or perhaps the schema changed? If yes, then update the warmup files accordingly"))
@@ -271,7 +271,7 @@ func (h *MainHelper) SetReplicationLagForTesting(seconds int) error {
 }
 
 func (h *MainHelper) execOnEachReplica(query string, args ...interface{}) error {
-	for _, replica := range h.SQLStore.Replicas {
+	for _, replica := range h.SQLStore.ReplicaXs {
 		_, err := replica.Exec(query, args...)
 		if err != nil {
 			return err