When the wasm_interface is destroyed, all unique_ptrs to the current instantiated modules are also destroyed. Unfortuately for some wasm runtimes -- wavm -- this incurs a lengthy garbage collection process for each module that is deleted. This can cause destruction of wasm_interface to take on the order of multiple minutes when there are thousands of instances! We need to violate the abstraction layer here and drop these instances on the floor during shutdown so the user isn't waiting minutes