DECRYPTION logs improper sourcetype

[FusionFC]

DECRYPTION logs should be sourcetype pan:decryption not pan:traffic

From the PA TA v7.0.4:

[pan_decryption]
DEST_KEY = MetaData:Sourcetype
REGEX = ^[^,]+,[^,]+,[^,]+,DECRYPTION,
FORMAT = sourcetype::pan:decryption