HPCC-9632 - Uninitialized lastCycles

'lastCycles' was left uninitialized until sink processes started
If the progress serialization requested timings before the sink
had started, totalMaxMs/totalMinMs timinigs would be wrong

Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>
Merge pull request #4604 from jakesmith/hpcc-9632

HPCC-9632 - Uninitialized lastCycles

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>