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
2 jobs for patch-1 in 17 minutes and 50 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Test
passed #664022
flatpak
flatpak devel

00:17:50

passed #664023
style check

00:01:28