testbench: bugfix: tcpflood must only be called via diag.sh
testbench: do not run test if required modules is not enabled
testbench: diag.sh tcpflood command did not handle quoted params properly
testbench: correctly quote tcpflood message parameter
bugfix: testbench did not abort on certain startup errors
testbench: do not run valgrind tests if valgrind is not present
testbench: omstdout is NOT required to run the testbench