mcv crate; cloak delay; AI... minor changes

MCV crate set to 0. This will be at the very least until there is a way to delay good units from showing up early game.
Cloak delay raised to 90 since it re-cloaks fast. This is because currently the stealth tank starts countdown while still in "attack mode", after the last missile was fired. Should be changed again to 1-2 seconds after  https://github.com/OpenRA/OpenRA/issues/2898 is implemented.
Added hard AI.