Bamboo instances upgraded from old versions still using MySQLDialect

Current versions of Bamboo are using this dialect:

<property name="hibernate.dialect">com.atlassian.hibernate.dialect.MySQL5Dialect</property>

Older versions used to use MySQLDialect (without the 5), and this property is not updated by any of the Bamboo upgrade tasks. This causes columns that should be created with varchar(4000) to instead be created as text. It can lead to errors in the logs while adding indices:
Unsuccessful: create index Error in Logs Using MySQL

We should have an upgrade task update the dialect automatically and notify that the change requires a restart.