Fix migration db connection failure. 

```
=== PREPARING TEST ENV
  - Starting [PUBSUB Component] -  2.711755146s
  - Starting [MYSQL Component] -  12.654525966s
  - Starting [MIGRATE Component] 2020/04/26 19:17:30
start err: migarton command filed:
error: dial tcp 172.18.0.3:3306: connect: connection refused
```