Core/Spells: Move Big Blizzard Bear implementation to spell script (#19544)

(cherry picked from commit 8a5b998f487bd1a391cc9d2d350c4a686b4e61b0)

src/server/game/Spells/SpellEffects.cpp

@@ -3345,24 +3345,6 @@ void Spell::EffectScriptEffect(SpellEffIndex effIndex)
 
                     return;
                 }
-                case 58983: // Big Blizzard Bear
-                {
-                    if (!unitTarget || unitTarget->GetTypeId() != TYPEID_PLAYER)
-                        return;
-
-                    // Prevent stacking of mounts and client crashes upon dismounting
-                    unitTarget->RemoveAurasByType(SPELL_AURA_MOUNTED);
-
-                    // Triggered spell id dependent on riding skill
-                    if (uint16 skillval = unitTarget->ToPlayer()->GetSkillValue(SKILL_RIDING))
-                    {
-                        if (skillval >= 150)
-                            unitTarget->CastSpell(unitTarget, 58999, true);
-                        else
-                            unitTarget->CastSpell(unitTarget, 58997, true);
-                    }
-                    return;
-                }
                 case 59317:                                 // Teleporting
                 {