chore(jetty): start even without pre-existing target directory
chore(jetty): start even without pre-existing target directory

related to CAM-5298

ingorichtsmeier/camunda-bpm-platform,ingorichtsmeier/camunda-bpm-platform,ingorichtsmeier/camunda-bpm-platform,langfr/camunda-bpm-platform,langfr/camunda-bpm-platform,ingorichtsmeier/camunda-bpm-platform,camunda/camunda-bpm-platform,camunda/camunda-bpm-platform,langfr/camunda-bpm-platform,camunda/camunda-bpm-platform,camunda/camunda-bpm-platform,ingorichtsmeier/camunda-bpm-platform,camunda/camunda-bpm-platform,ingorichtsmeier/camunda-bpm-platform,langfr/camunda-bpm-platform,langfr/camunda-bpm-platform,camunda/camunda-bpm-platform,langfr/camunda-bpm-platform