Invisible,impassable tiles on Tyrargo, in the USS Heyst insert

## Testmerges
#12947: 'Revert "Working multiz tacmap, round two, extra buttons"' by Rain7x at commit ea384007a4
#12627: 'Tyrargo Rift (2) - Various Alterations' by Steelpoint at commit f38ce6b980
#12967: 'Balance: Allows pill bottles to be forced open by bayonets' by antlersss at commit 98470554f7
#13037: 'Survivors now grant half a larva on permadeath but no extra on burst' by Drulikar at commit 73d6ec8fea
#13143: 'VSL without the V (Now with fixed dual-wielding!)' by Mary-Marilyn at commit 95273617b1
#11128: '[code beet] dissolver (used to be venator)' by cuberound at commit fa018b69f7
#13155: 'White Antre LZ Redesign + Rebalance Of Hull Walls' by Steelpoint at commit 17b6fb6e41
#12739: 'Sun mk3' by cuberound at commit 9bb5a5dd0d
#12464: 'LV1021: Operation Falcon's Fury - Ground Map' by Steelpoint at commit d198824bce

## Round ID
36435

## Description of the bug
Some invisible forcefield tiles to the south-southwest of the USS Heyst insert

## What's the difference with what should have happened?
Walkable tiles

## How do we reproduce this bug?
Tyrargo with the Heyst insert
Go East of comms to the dead medic by 2 crates and soft-point munition crate
see 3 impassable tiles north of each crate

## Attached logs
```
https://gyazo.com/014b25e383671ff4a2435396ac81bfa3
```

## Additional details
- Author: novacypher
- Admin: the novacypher
- Note: None

Reproduce the issue on Tyrargo with the USS Heyst insert, using the route east of comms to the dead medic and the two crates. Locate the three invisible impassable tiles north of the crates and correct them so the affected tiles are walkable, then verify the route in-game.

Written by the indexing model from the issue text.