tasks #7337: Remove users who unsubscribe from recipients

Change-Id: I2f18bcab27eb935c00967cd4d5f290bec603463d
Merge commit 'refs/changes/81/2881/7' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  tasks #7337: Remove users who unsubscribe from recipients

Change-Id: I4671096cd60fe19c0442572285a73c88bc610aa3
This is Tuleap 7.3.99.59

Change-Id: I048180e448dd111be3e32074914e37fa124a5d4e