Fix race condition bug in reporter
Fix race condition bug in reporter

Fixed a race where the report.reporters list got modified during
iteration and clean up reporter failure handling.

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