[backend/frontend] improve relationships distribution query (#3844)

[SouadHadjiat]

Proposed changes

• Fix targeted country dashboard query (we didn't return only countries ids, but also entities ids related to the countries, and return 100 results instead of 20)
• Set query results to 0 for aggregations (we only need aggregations), and use the limit param for aggregations size
• Add toRole param to have a more accurate filter (instead of *_to)

Related issues

• Dashboard crashes #3844

There is a performance issue with relations distribution query which can result to a timeout

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality => works locally, but I can't test the perf since I only have a small db
• I wrote test cases for the relevant uses case
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[helene-nguyen]

Tested locally and all good :)