Fix multi protocol traceroute test.
Fix multi protocol traceroute test.

Sharing the MTraceroute() instance amongst all the test methods leads to
problems.

kdmurray91/ooni-probe,juga0/ooni-probe,0xPoly/ooni-probe,Karthikeyan-kkk/ooni-probe,0xPoly/ooni-probe,lordappsec/ooni-probe,0xPoly/ooni-probe,0xPoly/ooni-probe,kdmurray91/ooni-probe,Karthikeyan-kkk/ooni-probe,kdmurray91/ooni-probe,kdmurray91/ooni-probe,lordappsec/ooni-probe,juga0/ooni-probe,juga0/ooni-probe,lordappsec/ooni-probe,juga0/ooni-probe,Karthikeyan-kkk/ooni-probe,Karthikeyan-kkk/ooni-probe,lordappsec/ooni-probe