DataFormatProvider implementations are found at runtime via the Java ServiceLoader infrastructure. The DomXmlDataFormatProvider is therefore declared in META-INF/services/org.camunda.spin.spi.DataFormatProvider file of the spin xml dataformat artifact.
You could remove that file (e.g. via Maven). If you are in JBoss/Wildfly and as an alternative, you could declare that a dependency to the xml data format module does not import the declared services. When you use Spin in combination with the process engine, you would have to edit the module descriptor of the spin process engine plugin for that purpose.
I hope that helps.
Cheers,
Thorben