Remove hardcoded numPlayersConfig, calculate it based on the maps land tiles 🔧 (#2874)

## Description:

The calculation is based on: 50 players per 1_000_000 land tiles,
limited at 125 players because of performance
Second number is 75% of that, third one 50%
That way, the player counts are staying mostly the same
Look at the "Dynamic Config" column, these are the new player counts:
(The 125 players limit is missing in that column, only relevant for the
twolakes map)

<img width="930" height="1033" alt="Screenshot_2026-01-12_152758"
src="https://github.com/user-attachments/assets/e1791740-e263-47b3-8b27-4f9aa358d381"
/>
<img width="926" height="324" alt="Screenshot_2026-01-12_152814"
src="https://github.com/user-attachments/assets/78d6789b-374f-4f8b-b50f-f6f08395572b"
/>

This PR also removes `MapDescription` from `Maps.ts` because its unused.
And this PR updates the map-generator `README.md` to reflect the changes

## Please complete the following:

- [X] I have added screenshots for all UI updates
- [X] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [X] I have added relevant tests to the test directory
- [X] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

FloPinguin

map-generator/README.md

@@ -105,10 +105,8 @@ The country will need to be added to `../src/client/data/countries.json`
 
 Using the `name` from your json:
 
-- Add to the MapDescription `../src/client/components/Maps.ts`
-- Add to the numPlayersConfig `../src/core/configuration/DefaultConfig.ts`
-- Add to the mapCategories `../src/core/game/Game.ts`
-- Add to the map playlist `../src/server/MapPlaylist.ts`
+- Add to GameMapType and mapCategories in `../src/core/game/Game.ts`
+- Add to the map playlist in `../src/server/MapPlaylist.ts`
 - Add to the `map` translation object in `../resources/lang/en.json`
 
 ## Notes