Improper singletons migration to clean Meyer's singletons (cherry-pick) (#2082)

# Pull Request

- Applies the clean and corrected singletons, Meyer pattern. (cherry
picked from @SmashingQuasar )

Testing by just playing the game in various ways. Been tested by myself
@Celandriel and @SmashingQuasar
---

## Complexity & Impact

- Does this change add new decision branches?
    - [x] No
    - [ ] Yes (**explain below**)

- Does this change increase per-bot or per-tick processing?
    - [x] No
    - [ ] Yes (**describe and justify impact**)

- Could this logic scale poorly under load?
    - [x] No
    - [ ] Yes (**explain why**)

---

## Defaults & Configuration

- Does this change modify default bot behavior?
    - [x] No
    - [ ] Yes (**explain why**)

---

## AI Assistance

- Was AI assistance (e.g. ChatGPT or similar tools) used while working
on this change?
    - [x] No
    - [ ] Yes (**explain below**)
---

## Final Checklist

- [x] Stability is not compromised
- [x] Performance impact is understood, tested, and acceptable
- [x] Added logic complexity is justified and explained
- [x] Documentation updated if needed

---

## Notes for Reviewers

Anything that significantly improves realism at the cost of stability or
performance should be carefully discussed
before merging.

---------

Co-authored-by: Nicolas Lebacq <nicolas.cordier@outlook.com>
Co-authored-by: Keleborn <22352763+Celandriel@users.noreply.github.com>

src/Ai/Base/Actions/MoveToRpgTargetAction.cpp

@@ -61,7 +61,7 @@ bool MoveToRpgTargetAction::Execute(Event event)
     }
 
     if ((unit && unit->isMoving() && !urand(0, 20)) || !ChooseRpgTargetAction::isFollowValid(bot, wo) ||
-        guidP.distance(bot) > sPlayerbotAIConfig->reactDistance * 2 || !urand(0, 50))
+        guidP.distance(bot) > sPlayerbotAIConfig.reactDistance * 2 || !urand(0, 50))
     {
         AI_VALUE(GuidSet&, "ignore rpg target").insert(AI_VALUE(GuidPosition, "rpg target"));
         RESET_AI_VALUE(GuidPosition, "rpg target");
@@ -73,7 +73,7 @@ bool MoveToRpgTargetAction::Execute(Event event)
     float z = wo->GetPositionZ();
     float mapId = wo->GetMapId();
 
-    if (sPlayerbotAIConfig->randombotsWalkingRPG)
+    if (sPlayerbotAIConfig.randombotsWalkingRPG)
         if (!bot->IsOutdoors())
             bot->m_movementInfo.AddMovementFlag(MOVEMENTFLAG_WALKING);