SoapUI can output JUnit style XML when running the command line runner (using the -j switch). This will produce a reports.xml file which is the one you want. See this page for more information. I'm not sure what this "soap.txt" report is.
I am not sure that report.xml is what I want. When I run teststeps and turn on exportAll it create txt report with some information of the teststep if it is valid or if it fail. And I want this txt report of each teststep convert to JUnit XML form.