fix kws web interface: no len_normalized_score

* earlier refacting removed it from KWS backend, but not from UI
- now in KWS UI we use 'score' instead of 'len_normalized_score'
* minor refactoring - use str.format
Merge pull request #4106 from dmwm/fix_kws_refactoring

fix kws web interface: use score instead of obsolete len_normalized_score