fix(analysis): fetch assignees by given models
fix(analysis): fetch assignees by given models

Until now, all assignees were fetched which resulted into significant
performance loss on the analysis page. With this, we fetch assignees
by the given tasks, projects or customers of the current page only.

adfinis-sygroup/timed-frontend,adfinis-sygroup/timed-frontend,adfinis-sygroup/timed-frontend