Fix TestFileManagerService on PostgreSQL

org.postgresql.util.PSQLException: ERROR: invalid byte sequence for encoding "UTF8": 0x00
	at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2455)
	at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2155)
	at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:460)
	at org.postgresql.jdbc.PgStatement.executeBatch(PgStatement.java:793)
	at org.postgresql.jdbc.PgPreparedStatement.executeBatch(PgPreparedStatement.java:1659)
	at org.tranql.connector.jdbc.StatementHandle.executeBatch(StatementHandle.java:155)
	at org.nuxeo.ecm.core.storage.sql.jdbc.JDBCRowMapper.insertSimpleRows(JDBCRowMapper.java:562)
	at org.nuxeo.ecm.core.storage.sql.jdbc.JDBCRowMapper.writeCreates(JDBCRowMapper.java:479)
	at org.nuxeo.ecm.core.storage.sql.jdbc.JDBCRowMapper.write(JDBCRowMapper.java:448)
	at sun.reflect.GeneratedMethodAccessor11.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.nuxeo.ecm.core.storage.sql.jdbc.JDBCMapperConnector.doInvoke(JDBCMapperConnector.java:42)
	at org.nuxeo.ecm.core.storage.sql.jdbc.JDBCMapperConnector.invoke(JDBCMapperConnector.java:85)
	at com.sun.proxy.$Proxy32.write(Unknown Source)
	at org.nuxeo.ecm.core.storage.sql.SoftRefCachingRowMapper.write(SoftRefCachingRowMapper.java:359)
	at org.nuxeo.ecm.core.storage.sql.SessionImpl.doFlush(SessionImpl.java:361)
	at org.nuxeo.ecm.core.storage.sql.SessionImpl.flush(SessionImpl.java:334)
	at org.nuxeo.ecm.core.storage.sql.SessionImpl.save(SessionImpl.java:313)
	at org.nuxeo.ecm.core.storage.sql.ra.ConnectionImpl.save(ConnectionImpl.java:174)
	at org.nuxeo.ecm.core.storage.sql.coremodel.SQLSession.save(SQLSession.java:142)
	at org.nuxeo.ecm.core.api.AbstractSession.save(AbstractSession.java:1413)
	at org.nuxeo.ecm.platform.filemanager.service.extension.AbstractFileImporter.create(AbstractFileImporter.java:242)
	at org.nuxeo.ecm.platform.filemanager.service.FileManagerService.createDocumentFromBlob(FileManagerService.java:225)
	at org.nuxeo.ecm.platform.filemanager.service.FileManagerService.createDocumentFromBlob(FileManagerService.java:208)
	at org.nuxeo.ecm.platform.filemanager.TestFileManagerService.testCreateBlobWithBlobMimetypeFallback(TestFileManagerService.java:358)