[UI String] Make hierarchy between the Product and Backends "hits" metric configurable

Review the microcopy for this Eng Jira: THREESCALE-8035

References:

See guidelines in the 3scale Microcopy Guide

Review the following description:

• checkbox : Do not count backend hits as product hits in this product
• Question mark:  When this is activated, Hits are only counted at product level. The backend level hits included in this product will not be counted as hits.

• Label: 
  Count product level hits only

Reference

• Marvel :https://marvelapp.com/prototype/5jci8g4/screen/85344594