[Bug]: Frequent `OnAdjacentTo` error

### Describe the Bug

Originates from #6093. The new `ZXA0003` unit seems to cause a bug with adjacency since adjacency expects a `Unit.EntityId` but `DummyUnit` does not assign `self.EntityId`.
The line numbers below are modified to include my warning code of which adjacent unit doesn't have the entity ID, the correct line is 787 instead of 790.
```
warning: adjacent unit does not have self.EntityId: zxa0003
warning: Error running OnAdjacentTo script in Entity ueb0302 at 1b9ffe08: ...\documents\github\fa\lua\sim\units\structureunit.lua(790): table index is nil
stack traceback:
...\documents\github\fa\lua\sim\units\structureunit.lua(790): in function <...\documents\github\fa\lua\sim\units\structureunit.lua:776>
```

### Reproduce the bug

Replay 23216422

### Screenshots

_No response_

### Additional context

_No response_