Investigate/fix test_service_checker_with_process_exit on backend T0/T1

[neethajohn]

duthosts = [<MultiAsicSonicHost> str2-7050qx-32s-acs-02]
enum_rand_one_per_hwsku_hostname = 'str2-7050qx-32s-acs-02'
@pytest.mark.disable_loganalyzer
def test_service_checker_with_process_exit(duthosts, enum_rand_one_per_hwsku_hostname):
duthost = duthosts[enum_rand_one_per_hwsku_hostname]
wait_system_health_boot_up(duthost)
with ConfigFileContext(duthost, os.path.join(FILES_DIR, IGNORE_DEVICE_CHECK_CONFIG_FILE)):
processes_status = duthost.all_critical_process_status()
containers = [x for x in list(processes_status.keys()) if x != "syncd" and x !="database"]
logging.info('Test containers: {}'.format(containers))
random.shuffle(containers)
for container in containers:
running_critical_process = processes_status[container]['running_critical_process']
if not running_critical_process:
continue
critical_process = random.sample(running_critical_process, 1)[0]
with ProcessExitContext(duthost, container, critical_process):
time.sleep(DEFAULT_INTERVAL)
value = redis_get_field_value(duthost, STATE_DB, HEALTH_TABLE_NAME, '{}:{}'.format(container, critical_process))
>                   assert value == "'{}' is not running".format(critical_process), 'Got value {}'.format(value)
E                   AssertionError: Got value
container  = 'snmp'
containers = ['pmon', 'snmp', 'lldp', 'swss', 'teamd', 'bgp']
critical_process = 'snmp-subagent'
duthost    = <MultiAsicSonicHost> str2-7050qx-32s-acs-02
duthosts   = [<MultiAsicSonicHost> str2-7050qx-32s-acs-02]
enum_rand_one_per_hwsku_hostname = 'str2-7050qx-32s-acs-02'
processes_status = {'bgp': {'exited_critical_process': [], 'running_critical_process': ['bgpcfgd', 'bgpd', 'fpmsyncd', 'staticd', 'zebra'...pmgrd'], 'status': True}, 'pmon': {'exited_critical_process': [], 'running_critical_process': [], 'status': True}, ...}
running_critical_process = ['snmp-subagent', 'snmpd']
value      = ''
x          = 'swss'
system_health/test_system_health.py:116: AssertionError