HPCC-12128 - MP connections take too long

When A-> B and B->A within a very short time frame a 3 minute delay would often occur after which a failed connection might still occur.  This was noticed very often when using the mptests, which are used for new mp lib development.

Signed-off-by: Mark Kelly <mark.kelly@lexisnexis.com>
As connect() (and closeSocket()) is always called inside connectcrit,
the only exception where is attachSocket where ismaster=false, i.e. call from CMPConnectThread::run.

Do you need an extra crit, could you ensure that both calls to attachSocket were in connectcrit?