Fix #6438: Properly invalidate AI Settings window when max no competitor setting is changed.

src/ai/ai_gui.cpp

@@ -875,7 +875,6 @@ struct AIConfigWindow : public Window {
 					new_value = min(MAX_COMPANIES - 1, GetGameSettings().difficulty.max_no_competitors + 1);
 				}
 				IConsoleSetSetting("difficulty.max_no_competitors", new_value);
-				this->InvalidateData();
 				break;
 			}
 

src/settings.cpp

@@ -1174,6 +1174,7 @@ static bool MaxNoAIsChange(int32 i)
 		ShowErrorMessage(STR_WARNING_NO_SUITABLE_AI, INVALID_STRING_ID, WL_CRITICAL);
 	}
 
+	InvalidateWindowClassesData(WC_GAME_OPTIONS, 0);
 	return true;
 }