CSW - Improve "disableWeaponAssembly" status effect usage

[johnb432]

When merged this pull request will:

• Turn off vanilla assembly for placed tripods and assembled CSWs, so that FUNC(initVehicle) can handle enabling/disabling vanilla assembly when the QGVAR(assemblyMode) is set on the vehicle.
• Only set the status effect where the gunner's turret is local. Until now, every machine set a status effect that has a global effect, which is useless.
• Removed the execNextFrame in FUNC(initVehicle), because it runs 1 second after a vehicle has been created, so no need for the frame of delay.
• Optimised FUNC(staticWeaponInit_unloadExtraMags) slightly (from CSW - Rework settings #9901).

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