[8.0] Improve HNSW-parallel tests - [MOD-7970] (#579)

Improve HNSW-parallel tests - [MOD-7970] (#576)

* refactor tests

* format

* fix helper function

* fix range ties

(cherry picked from commit 18afddb)

Co-authored-by: GuyAv46 <[email protected]>

Author: github-actions[bot]