nominatim: increase number of tracked connections
nominatim: increase number of tracked connections

The number of established connections has almost doubled since
the update to Ubuntu 20.04.

tomhughes/openstreetmap-chef,tomhughes/openstreetmap-chef,tomhughes/openstreetmap-chef,openstreetmap/chef,openstreetmap/chef,zerebubuth/openstreetmap-chef,tomhughes/openstreetmap-chef,openstreetmap/chef,zerebubuth/openstreetmap-chef,zerebubuth/openstreetmap-chef,zerebubuth/openstreetmap-chef,openstreetmap/chef,openstreetmap/chef,tomhughes/openstreetmap-chef,zerebubuth/openstreetmap-chef,openstreetmap/chef,tomhughes/openstreetmap-chef,openstreetmap/chef,zerebubuth/openstreetmap-chef,openstreetmap/chef,zerebubuth/openstreetmap-chef,tomhughes/openstreetmap-chef,tomhughes/openstreetmap-chef,zerebubuth/openstreetmap-chef