[OSTF] OSTF fails after deployment HA environment with Cinder, Neutron and network template for MOS 8.0

[Alexander Gromov]

This problem is often reproduced on CI:
https://patching-ci.infra.mirantis.net/job/8.0.system_test.ubuntu.network_templates/8/testReport/%28root%29/network_config_consistency_on_reboot/
https://patching-ci.infra.mirantis.net/job/8.0.system_test.ubuntu.network_templates/12/testReport/%28root%29/network_config_consistency_on_reboot/
https://patching-ci.infra.mirantis.net/job/8.0.system_test.ubuntu.network_templates/15/testReport/%28root%29/network_config_consistency_on_reboot/
https://patching-ci.infra.mirantis.net

Steps to reproduce:
1. Revert snapshot with 5 slaves
2. Create cluster (HA) with Neutron VLAN
3. Add 3 controller and 1 compute + cinder nodes
4. Upload 'default_ovs' network template
5. Create custom network groups basing
6. Run network verification
7. Deploy cluster and run basic health checks
8. Run network verification
9. Check L3 network configuration on slaves
10. Check that services are listening on their networks only
11. Reboot a node
12. Run network verification
13. Check L3 network configuration on slaves
14. Check that services are listening on their networks only
15. Run OSTF

Expected results:
All steps pass

Actual result:
OSTF test fails with the following error:
AssertionError: Failed 1 OSTF tests; should fail 0 tests. Names of failed tests:
  - Check network connectivity from instance via floating IP (failure) VM connectivity doesn`t function properly. Please refer to OpenStack logs for more details.