MAL_MAXCLIENTS: no longer require threads workers per client
MAL_MAXCLIENTS: no longer require threads workers per client

Since all clients use a shared pool of workers, we no longer need the
blow-up of threads * clients.

zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb