Fix utf8mb4 on vendor tables

Fix utf8mb4 on vendor tables

When creating the schema for test these tables use default length for
string: 255. Which fail when using utf8mb4.

> Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes

Also move the `setKeepStaticConnections` in before and after class to
avoid:

> SAVEPOINT DOCTRINE2_SAVEPOINT_2 does not exist

See https://github.com/dmaicher/doctrine-test-bundle#troubleshooting