PerconaFormattedSqlChangeLogParser should be disabled if liquibase.percona.defaultOn=false

[westse]

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Issues like #491 are still encountered even when liquibase.percona.defaultOn=false (and the changeset-specific usePercona property is not set or set to false). In this case the expected behavior should instead be identical to FormattedSqlChangeLogParser, and to avoid any logic that may modify the changeset.