testplanet: support snapshot based migration for storagenode

Similar to the existing snapshot based tests of satellite/metabase db we make a migration here which is:
 * dedicated to unit tests
 * faster (with less steps)
 * but safe: additional unit test ensures that the snapshot based migration and normal prod migration have the same results.

Change-Id: Ie324b09f64b4553df02247a9461ece305a6cf832

private/testplanet/storagenode.go

@@ -257,7 +257,7 @@ func (planet *Planet) newStorageNode(ctx context.Context, prefix string, index,
 	// Mark the peer's PieceDeleter as in testing mode, so it is easy to wait on the deleter
 	peer.Storage2.PieceDeleter.SetupTest()
 
-	err = db.MigrateToLatest(ctx)
+	err = db.TestMigrateToLatest(ctx)
 	if err != nil {
 		return nil, err
 	}

storagenode/peer.go

@@ -76,6 +76,10 @@ var (
 type DB interface {
 	// MigrateToLatest initializes the database
 	MigrateToLatest(ctx context.Context) error
+
+	// TestMigrateToLatest is a fast migration with skipping test (not safe for production + old db state)
+	TestMigrateToLatest(ctx context.Context) error
+
 	// Close closes the database
 	Close() error
 

storagenode/storagenodedb/database.go

@@ -347,6 +347,13 @@ func (db *DB) MigrateToLatest(ctx context.Context) error {
 	return migration.Run(ctx, db.log.Named("migration"))
 }
 
+// TestMigrateToLatest creates any necessary tables from snapshot.
+// it's faster for the testing but should be the same as MigrateToLatest.
+func (db *DB) TestMigrateToLatest(ctx context.Context) error {
+	migration := db.Snapshot(ctx)
+	return migration.Run(ctx, db.log.Named("migration"))
+}
+
 // Preflight conducts a pre-flight check to ensure correct schemas and minimal read+write functionality of the database tables.
 func (db *DB) Preflight(ctx context.Context) (err error) {
 	for dbName, dbContainer := range db.SQLDBs {