Core/Spells: Merge TRIGGERED_IGNORE_AURA_INTERRUPT_FLAGS functionality into TRIGGERED_IGNORE_CAST_IN_PROGRESS as they are always used together (and missing one of them in scripts is a common enough mistake)

* Also fixes Ray of Frost being interrupted by casting Shimmer

src/server/game/Spells/Spell.cpp

@@ -3434,7 +3434,7 @@ SpellCastResult Spell::prepare(SpellCastTargets const& targets, AuraEffect const
         {
             // stealth must be removed at cast starting (at show channel bar)
             // skip triggered spell (item equip spell casting and other not explicit character casts/item uses)
-            if (!(_triggeredCastFlags & TRIGGERED_IGNORE_AURA_INTERRUPT_FLAGS) && !m_spellInfo->HasAttribute(SPELL_ATTR2_NOT_AN_ACTION))
+            if (!(_triggeredCastFlags & TRIGGERED_IGNORE_CAST_IN_PROGRESS) && !m_spellInfo->HasAttribute(SPELL_ATTR2_NOT_AN_ACTION))
                 unitCaster->RemoveAurasWithInterruptFlags(SpellAuraInterruptFlags::Action, m_spellInfo);
 
             unitCaster->SetCurrentCastSpell(this);
@@ -3792,7 +3792,7 @@ void Spell::_cast(bool skipCheck)
     if (!(hitMask & PROC_HIT_CRITICAL))
         hitMask |= PROC_HIT_NORMAL;
 
-    if (!(_triggeredCastFlags & TRIGGERED_IGNORE_AURA_INTERRUPT_FLAGS) && !m_spellInfo->HasAttribute(SPELL_ATTR2_NOT_AN_ACTION))
+    if (!(_triggeredCastFlags & TRIGGERED_IGNORE_CAST_IN_PROGRESS) && !m_spellInfo->HasAttribute(SPELL_ATTR2_NOT_AN_ACTION))
         m_originalCaster->RemoveAurasWithInterruptFlags(SpellAuraInterruptFlags::ActionDelayed, m_spellInfo);
 
     Unit::ProcSkillsAndAuras(m_originalCaster, nullptr, procAttacker, PROC_FLAG_NONE, PROC_SPELL_TYPE_MASK_ALL, PROC_SPELL_PHASE_CAST, hitMask, this, nullptr, nullptr);

src/server/game/Spells/SpellDefines.h

@@ -171,7 +171,7 @@ enum TriggerCastFlags : uint32
     TRIGGERED_IGNORE_CAST_IN_PROGRESS               = 0x00000020,   //! Will not check if a current cast is in progress
     TRIGGERED_IGNORE_COMBO_POINTS                   = 0x00000040,   //! Will ignore combo point requirement
     TRIGGERED_CAST_DIRECTLY                         = 0x00000080,   //! In Spell::prepare, will be cast directly without setting containers for executed spell
-    TRIGGERED_IGNORE_AURA_INTERRUPT_FLAGS           = 0x00000100,   //! Will ignore interruptible aura's at cast
+    // reuse                                        = 0x00000100,
     TRIGGERED_IGNORE_SET_FACING                     = 0x00000200,   //! Will not adjust facing to target (if any)
     TRIGGERED_IGNORE_SHAPESHIFT                     = 0x00000400,   //! Will ignore shapeshift checks
     TRIGGERED_IGNORE_CASTER_AURASTATE               = 0x00000800,   //! Will ignore caster aura states including combat requirements and death state