BF-41628 found that if fassertOnLockTimeoutForStepUpDown = 0 (no timeout for RSTL acquisition), the new deadline introduced in SERVER-119490 and SERVER-117908 does not account for this case correctly and passes a deadline of Date_t::now() + 0, which causes the kill op thread to almost immediately time out.

If this param is 0, we should pass Date_t::max(), which is the default deadline for all other usages of the kill op thread.