Add model name to warning message

[sasharevzin]

I find [searchkick] WARNING: Records in search index do not exist in database: 4598, 5450, 6192, 6216, 7018, 7245, 7266 unclear to which model these ids related. For better understanding, I would like to add the model name so that it will look like [searchkick] WARNING: User records in search index do not exist in the database: 4598, 5450, 6192, 6216, 7018, 7245, 7266