Make easy difficulty easier 📊 (#3072)

## Description:


https://www.reddit.com/r/Openfront/comments/1qquvdg/difficulty_scaling_in_single_player/
People seem to feel that easy is not easy enough, even after the various
nerfs in multiple places.
So let's touch DefaultConfig.

## 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

src/core/configuration/DefaultConfig.ts

@@ -725,7 +725,7 @@ export class DefaultConfig implements Config {
     if (playerInfo.playerType === PlayerType.Nation) {
       switch (this._gameConfig.difficulty) {
         case Difficulty.Easy:
-          return 18_750;
+          return 12_500;
         case Difficulty.Medium:
           return 25_000; // Like humans
         case Difficulty.Hard:
@@ -760,7 +760,7 @@ export class DefaultConfig implements Config {
 
     switch (this._gameConfig.difficulty) {
       case Difficulty.Easy:
-        return maxTroops * 0.75;
+        return maxTroops * 0.5;
       case Difficulty.Medium:
         return maxTroops * 1; // Like humans
       case Difficulty.Hard:
@@ -787,7 +787,7 @@ export class DefaultConfig implements Config {
     if (player.type() === PlayerType.Nation) {
       switch (this._gameConfig.difficulty) {
         case Difficulty.Easy:
-          toAdd *= 0.95;
+          toAdd *= 0.9;
           break;
         case Difficulty.Medium:
           toAdd *= 1; // Like humans