[s1907] Don't send Spell::CheckCast fail result for passive auras

No need to notify client when a passive aura failed to cast (like using Cat Form indoor with Feral Swiftness talent learned).

Contributor Maxxie.

(based on commit [12373] - 66d4653)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>