Core/Spells: Rename more SpellAttr9 to official names

Port From (https://github.com/TrinityCore/TrinityCore/commit/8963ea8e4c215e750aa7a473bbf780b403dc8839)

Source/Framework/Constants/Spells/SpellConst.cs

@@ -1980,9 +1980,9 @@ namespace Framework.Constants
         AllowWhileBanishedAuraState = 0x800, // Doesn't seem to be doing anything, banish behaves like a regular stun now - tested on patch 10.2.7 with spell 17767 (doesn't have this attribute, only SPELL_ATTR5_ALLOW_WHILE_STUNNED and was castable while banished)
         FaceUnitTargetUponCompletionOfJumpCharge = 0x1000, // Face unit target upon completion of jump charge
         HasteAffectsMeleeAbilityCasttime = 0x2000, // Haste Affects Melee Ability Casttime
-        UsableInRatedBattlegrounds = 0x4000, // 14 Can Be Used In Rated Battlegrounds
-        Unk15 = 0x8000, // 15
-        Unk16 = 0x10000, // 16
+        IgnoreDefaultRatedBattlegroundRestrictions = 0x4000, // Ignore Default Rated Battleground Restrictions
+        DoNotDisplayPowerCost = 0x8000, // Do Not Display Power Cost (client only)
+        NextModalSpellRequiresSameUnitTarget = 0x10000, // Prevents automatically casting the spell from SpellClassOptions::ModalNextSpell after current spell if target was changed (client only)
         Unk17 = 0x20000, // 17
         Unk18 = 0x40000, // 18
         Unk19 = 0x80000, // 19

Source/Game/Spells/Spell.cs

@@ -6425,7 +6425,7 @@ namespace Game.Spells
 
             // check USABLE attributes
             // USABLE takes precedence over NOT_USABLE
-            if (isRatedBattleground && m_spellInfo.HasAttribute(SpellAttr9.UsableInRatedBattlegrounds))
+            if (isRatedBattleground && m_spellInfo.HasAttribute(SpellAttr9.IgnoreDefaultRatedBattlegroundRestrictions))
                 return SpellCastResult.SpellCastOk;
 
             if (isArena && m_spellInfo.HasAttribute(SpellAttr4.IgnoreDefaultArenaRestrictions))