[iwd] Minor issues in the lich areas - covered container, potential dupe items

[CamDawg]

This came up while troubleshooting some Tweaks stuff. Two minor items:

• In the Hall of Heroes (ar6006) two containers are on top of one another (labeled as containers 4 and 9). One contains the Blessed Helm of Lathander, and the other contains a Potion of Insulation and a Spell Thrust scroll.
• Both the Hall of Heroes and the Tiers of the Dead (ar6005) contain the same random treasure (rndtre57, ud5tres in the original). This resolves to one of three items: Short Sword of Shadows +3 (uSswd4a), Bastard Sword +2: Conflagration (uBswd4c), or Hold Fast +3 (uLswd4a).

For the former, I suggest we disable one container and combine the loot into the other. Alternatively, we can move one of them to cover a different tomb.

The latter is one of those that I think is a bug, but the fix can go a number of ways. We can simply delete one instance (which one?) or substitute it (with what?). And while the u-items aren't strictly unique, potentially getting one of those items in consecutive areas feels very weird, especially since it's a good chance (33%) since it's a small random drop.

[CamDawg]

I've combined these into one fix: the inaccessible container in the Hall of Heroes has been deleted, and its contents (Potion of Insulation, Spell Thrust scroll) have been moved into the container that formerly held the duplicated random drop.