Refactor timeout scaling factor initialization In order to stabilize tests on (heavily loaded) CI infrastructure, reasses scaling factor every three minutes. Also include (simple) I/O benchmark to compensate for (overloaded) I/O subsystem of CI slaves. For details, see `Builder::TestReport::Result >> timeoutScale`

../../../projects/smalltalk/stx -I --noBanner  -f report-runner.st -D /tmp -r Builder::TestReport -p exept:regression