chutney: Bump the data size transmitted with the verify command
With legacy/trac#29263 (moved), the SENDMEs can be tested properly but as long as the circuits has more than 500KB on it (which is roughly the 512 byte data cell size times the circuit window start of 1000).
To be safe, having let say 600KB of data transmitted with
chutney verify would be a sure test of the circuit flow control feature. And it doesn't take much more time at all from what we have right now.
On slow systems like arm64 for instance, there could be an argument to bump the SOCKS timeout from 3 to let say 5 or 10 seconds in order to avoid chutney killing the connections before 600KB went through the circuit.