[test_system_health] add dockers check after critical processes resta…

…rt (#4960)

Signed-off-by: Anton <antonh@nvidia.com>

Summary:
Fixed test issue in which the dockers can be restarted.
If restart some critical processes, as coppmgrd in swss, all the dockers can be restarted. The restart starts after "start" of the process.
To avoid failure of next tests, added a check of critical processes at the end of the "problematic" test.

tests/system_health/test_system_health.py

@@ -10,6 +10,7 @@
 from tests.common.helpers.assertions import pytest_require
 from tests.platform_tests.thermal_control_test_helper import disable_thermal_policy
 from device_mocker import device_mocker_factory
+from tests.common.helpers.assertions import pytest_assert
 
 pytestmark = [
     pytest.mark.topology('any')
@@ -384,3 +385,6 @@ def __enter__(self):
     def __exit__(self, exc_type, exc_val, exc_tb):
         logging.info('Starting {}:{}'.format(self.container_name, self.process_name))
         self.dut.command('docker exec -it {} bash -c "supervisorctl start {}"'.format(self.container_name, self.process_name))
+        # check with delay in which the dockers can be restarted
+        pytest_assert(wait_until(300, 20, 8, self.dut.critical_services_fully_started),
+                      "Not all critical services are fully started")