mention _sprintf_p in top comment & shorten test string to vertically align tests; #4531
mention _sprintf_p in top comment & shorten test string to vertically align tests; #4531

vlulla/data.table,Rdatatable/data.table,vlulla/data.table,jangorecki/data.table,Rdatatable/data.table,vlulla/data.table,Rdatatable/data.table,Rdatatable/data.table,jangorecki/data.table,vlulla/data.table,jangorecki/data.table,jangorecki/data.table