Core/Movement: Clean up and improvements on Unit::SetSpeed (#16843)

- Clean up of Unit::SetSpeed (mostly cherry picks from the 6.x branch):
- the opcode sent depends on the unit. until now, MSG_MOVE_SET_* were sent for every units which isn't like retail behavior.
- Removed the unused method parameter "forced" from Unit::SetSpeed
- Renamed Unit::SetSpeed to SetSpeedRate
- Removed the unused method parameter "forced" from Unit::UpdateSpeed
- Added utility method Unit::SetSpeed which take the new flat value.
(cherry picked from commit dc3327f9c5f80c36000356829159c060d916f62b)

# Conflicts:
#	src/server/game/Entities/Unit/Unit.cpp
#	src/server/game/Handlers/MovementHandler.cpp
#	src/server/scripts/EasternKingdoms/ZulAman/boss_akilzon.cpp
#	src/server/scripts/EasternKingdoms/ZulAman/boss_nalorakk.cpp
#	src/server/scripts/EasternKingdoms/ZulAman/boss_zuljin.cpp
#	src/server/scripts/Kalimdor/zone_azshara.cpp
#	src/server/scripts/Kalimdor/zone_durotar.cpp
#	src/server/scripts/Outland/zone_hellfire_peninsula.cpp

1 files changed, 1 insertions, 1 deletions

diff --git a/src/server/scripts/EasternKingdoms/ScarletMonastery/boss_headless_horseman.cpp b/src/server/scripts/EasternKingdoms/ScarletMonastery/boss_headless_horseman.cpp
index a99b7b20103..fb9cd7b6742 100644
--- a/src/server/scripts/EasternKingdoms/ScarletMonastery/boss_headless_horseman.cpp
+++ b/src/server/scripts/EasternKingdoms/ScarletMonastery/boss_headless_horseman.cpp
@@ -450,7 +450,7 @@ public:
             me->SetVisible(false);
             me->SetFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NON_ATTACKABLE);
             me->SetDisableGravity(true);
-            me->SetSpeed(MOVE_WALK, 5.0f, true);
+            me->SetSpeedRate(MOVE_WALK, 5.0f);
             wp_reached = false;
             count = 0;
             say_timer = 3000;