search-engine-tracker: Fix query string in different system formats
The search-engine-tracker builds a query string by using a float number "FILENAME_RANK".
But, in different system formats that use 'comma' instead of 'dot' as decimal separator, this query string produces an error and the 'tracker engine' fails, doesn't returning nothing.
The solution was to change the "FILENAME_RANK" in the from float to integer to avoid using 'dot' or 'comma' separator in the query string.
Fixes: #1412 (closed)