[Tests] Implement cleanup routines for created users, hosts, rules etc

[miskopo]

Description of a problem:

Currently, the only functional clean-up is for test users, and that only if there are less than one page of them. When running tests locally repeatedly, manual clean-up is required for entries like hosts, rules etc.

Affected environment

This issue is relevant only for local env, as in the GH CI, server is destroyed and recreated for each CI run.

Possible solution

Implement universal clean-up solution for all kinds of entries and execute it prior to testing.