fix(Core/Grid): Address bugs and performance issues introduced by visibility notifier implementation (#17480)

* Bug fixes

- Corrected std::chrono from seconds to milliseconds
- Got rid of leftover code that caused objects to not show up on time

* Removed logic to set gameobject as active

- More alignement with TC.
- Reduces CPU usage drastically

* Revert back to using time_t instead of std chrono

* Invoke SetNoCreate() method to reduce CPU usage drastically

* Remove setActive from static and motion transports

* Fix performance issues

* Added SetFarVisible to WG and some dungeon scripts

- Also removed setActive(true) from creatures in Wintergrasp. As for gameobjects they are set to active upon being damaged/destroyed and removed from active on rebuild (reset)

* Removed comments related to VISIBILITY_COMPENSATION

* Fix log

* Deleted unused files + corrected a check

* Added missing header

* Removed unused parameter

* Removed another unsued parameter

* Changed vector to set for i_visibleNow

- Changed vector to set for i_visibleNow in VisibleNotifer
- Adjusted HaveAtClient to accept Object*
- Adjusted SendUpdateToPlayer to send createobject packet only if not known to client

src/server/scripts/EasternKingdoms/BlackrockMountain/BlackwingLair/boss_nefarian.cpp

@@ -327,6 +327,7 @@ public:
                     if (Creature* nefarian = me->SummonCreature(NPC_NEFARIAN, NefarianSpawn))
                     {
                         nefarian->setActive(true);
+                        nefarian->SetFarVisible(true);
                         nefarian->SetCanFly(true);
                         nefarian->SetDisableGravity(true);
                         nefarian->GetMotionMaster()->MovePath(NEFARIAN_PATH, false);

src/server/scripts/EasternKingdoms/BlackrockMountain/BlackwingLair/instance_blackwing_lair.cpp

@@ -425,6 +425,7 @@ public:
                         {
                             nefarius->SetPhaseMask(1, true);
                             nefarius->setActive(true);
+                            nefarius->SetFarVisible(true);
                             nefarius->Respawn();
                             nefarius->GetMotionMaster()->MoveTargetedHome();
                         }

src/server/scripts/EasternKingdoms/Karazhan/boss_nightbane.cpp

@@ -105,6 +105,7 @@ struct boss_nightbane : public BossAI
         me->SetDisableGravity(_intro);
         me->SetWalk(false);
         me->setActive(true);
+        me->SetFarVisible(true);
 
         if (instance)
         {

src/server/scripts/EasternKingdoms/ScarletEnclave/zone_the_scarlet_enclave.cpp

@@ -55,6 +55,7 @@ public:
         void Reset() override
         {
             me->setActive(true);
+            me->SetFarVisible(true);
             me->SetVisible(false);
             me->SetUnitFlag(UNIT_FLAG_NON_ATTACKABLE);
             me->SetCanFly(true);