Add new Bering Sea map, reduce Strait rotation (#3706)

## Description:

Re-submission of older PR:
https://github.com/openfrontio/OpenFrontIO/pull/3617
<img width="612" height="396" alt="image"
src="https://github.com/user-attachments/assets/955a0b2e-1df9-4fa3-a389-235f46a90f69"
/>

Regarding Bering Sea and Bering strait maps:
<img width="576" height="87" alt="image"
src="https://github.com/user-attachments/assets/f57031eb-f9c0-4e1e-83ff-204df51bb6c2"
/>
<img width="589" height="93" alt="image"
src="https://github.com/user-attachments/assets/629e71ba-489f-41cf-b67e-2476af8704f2"
/>

Because of mixed opinions about replacing the maps, i propose at least
this temporary compromise: Bering Sea gets added as a new map and Bering
Strait gets its rotation lowered to a small number. Since the classic
maps are probably being taken off rotation, we should have some small
breathing space for the 2 maps.

In the near future we should discuss between mapmakers in the dev server
whether we keep, replace or completely take Bering Strait off rotation,
and/or a community poll.

## 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:

tri.star1011

src/server/MapPlaylist.ts

@@ -72,7 +72,7 @@ const frequency: Partial<Record<GameMapName, number>> = {
   Didier: 1,
   AmazonRiver: 3,
   BosphorusStraits: 3,
-  BeringStrait: 4,
+  BeringStrait: 2,
   Sierpinski: 10,
   TheBox: 3,
   Yenisei: 6,
@@ -91,6 +91,7 @@ const frequency: Partial<Record<GameMapName, number>> = {
   Luna: 6,
   Conakry: 3,
   Caucasus: 5,
+  BeringSea: 5,
 };
 
 const TEAM_WEIGHTS: { config: TeamCountConfig; weight: number }[] = [