Fix Flyway mismatch workaround in legacy branch

[wadimw]

Workaround cherry-picked in #1034 is fragile because it relies on a specific error message. It turns out that this error message is different in legacy Mojito (probably due to older Spring Boot and Flyway). This PR adjusts the message content matched by workaround to make it work properly in legacy Mojito.

Actual error message that we got in logs is:

caused by: org.flywaydb.core.api.flywayexception: validate failed. migration checksum mismatch for migration 1
-> applied to database : 147381909
-> resolved locally    : -1294323746
	at org.flywaydb.core.flyway.dovalidate(flyway.java:1108)
	at org.flywaydb.core.flyway.access$300(flyway.java:62)
	at org.flywaydb.core.flyway$1.execute(flyway.java:1012)
	at org.flywaydb.core.flyway$1.execute(flyway.java:1006)
	at org.flywaydb.core.flyway.execute(flyway.java:1418)
	at org.flywaydb.core.flyway.migrate(flyway.java:1006)
	at com.box.l10n.mojito.flywayconfig$1.migrate(flywayconfig.java:50)
	at org.springframework.boot.autoconfigure.flyway.flywaymigrationinitializer.afterpropertiesset(flywaymigrationinitializer.java:63)
	at org.springframework.beans.factory.support.abstractautowirecapablebeanfactory.invokeinitmethods(abstractautowirecapablebeanfactory.java:1637)
	at org.springframework.beans.factory.support.abstractautowirecapablebeanfactory.initializebean(abstractautowirecapablebeanfactory.java:1574)
	... 179 more