Remove WifiUtils calls in tel_test_utils.py.

Fix the wifi_tethering_cleanup failure.

Test: run test in the lab
Bug: 26294018
Change-Id: I475a641def8f97d13e2e371495b147033e6d6328
diff --git a/acts/tests/google/tel/live/TelLivePreflightTest.py b/acts/tests/google/tel/live/TelLivePreflightTest.py
index 120e74a..af60a86 100644
--- a/acts/tests/google/tel/live/TelLivePreflightTest.py
+++ b/acts/tests/google/tel/live/TelLivePreflightTest.py
@@ -35,7 +35,6 @@
 from acts.test_utils.tel.tel_defines import WAIT_TIME_AFTER_REBOOT
 from acts.test_utils.tel.tel_lookup_tables import device_capabilities
 from acts.test_utils.tel.tel_lookup_tables import operator_capabilities
-from acts.test_utils.tel.tel_test_utils import WifiUtils
 from acts.test_utils.tel.tel_test_utils import abort_all_tests
 from acts.test_utils.tel.tel_test_utils import ensure_phones_default_state
 from acts.test_utils.tel.tel_test_utils import ensure_wifi_connected
@@ -47,6 +46,7 @@
 from acts.test_utils.tel.tel_test_utils import verify_http_connection
 from acts.test_utils.tel.tel_test_utils import wait_for_voice_attach_for_subscription
 from acts.test_utils.tel.tel_test_utils import wait_for_wifi_data_connection
+from acts.test_utils.tel.tel_test_utils import wifi_toggle_state
 from acts.test_utils.tel.tel_voice_utils import phone_setup_volte
 from acts.asserts import abort_all
 from acts.asserts import fail
@@ -80,7 +80,7 @@
                     not verify_http_connection(self.log, ad)):
                 abort_all_tests(ad.log, "Data not available on WiFi")
         finally:
-            WifiUtils.wifi_toggle_state(self.log, ad, False)
+            wifi_toggle_state(self.log, ad, False)
         # TODO: add more environment check here.
         return True