2023-10-23: AoE2DE Mountain Royals DLC changes

Copied from ~Jp (World's Edge Server Engineer):

Hey @everyone,

Here are the new mappings that will be going live with The Mountain Royals DLC.

Here is a recap of what has changed and what hasn't since the release of the Return of Rome DLC:

* The Options string and Match Types have not changed.

* Mapping #3 is the mapping for the June CU up until now.

* It has the fixed map IDs in it (-2 → fixed map ID).

* Mapping #4 is the mapping for the current PUP and will be going live on the 31st with The Mountain Royals DLC.

• This has the updated civilization IDs in it.