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`
*.sth
*.STH
*.sc
objbc
objvc
objmingw
*.res
ntLibInit.c
*.log
results
modules
st.chg
*.c