Fix TestBuggyProducer.shouldStopOnProducerError on MySQL

java.lang.AssertionError: Count of documents that should have been created after import expected:<80> but was:<0>
	at org.junit.Assert.fail(Assert.java:88)
	at org.junit.Assert.failNotEquals(Assert.java:743)
	at org.junit.Assert.assertEquals(Assert.java:118)
	at org.junit.Assert.assertEquals(Assert.java:555)
	at org.nuxeo.ecm.platform.importer.queue.tests.TestBuggyProducer.shouldStopOnProducerError(TestBuggyProducer.java:80)