[z1843] Improve db error log output for *_addon auras

This clearifies that a problem is caused by already applied auras and not double aura in *_addon table.
The double spell entry as well as the invalid spell are filtered on load.

Signed-off-by: Schmoozerd <schmoozerd@scriptdev2.com>

(based on commit 6c3f35d)

(cleaned version of c5d62cf)

(based on commit [s1404] - cab5ab4)