[PSM Interop] Add a step to wait for active XDS channel when start test client. (#34631)
* Logs when XDS channel check passed:
```
I1010 22:53:35.013700 140608769881920 client_app.py:278] [psm-grpc-client-9b5756c77-4gv6d] Waiting to report an active channel to trafficdirector.googleapis.com:443
I1010 22:53:38.879174 140608769881920 client_app.py:306] [psm-grpc-client-9b5756c77-4gv6d] xds channel: <Channel channel_id=10 target=trafficdirector.googleapis.com:443 call_started=2 calls_failed=2 state=READY>
I1010 22:53:49.002596 140608769881920 client_app.py:306] [psm-grpc-client-9b5756c77-4gv6d] xds channel: <Channel channel_id=10 target=trafficdirector.googleapis.com:443 call_started=5 calls_failed=5 state=READY>
I1010 22:53:59.130141 140608769881920 client_app.py:306] [psm-grpc-client-9b5756c77-4gv6d] xds channel: <Channel channel_id=10 target=trafficdirector.googleapis.com:443 call_started=6 calls_failed=6 state=READY>
I1010 22:54:09.253418 140608769881920 client_app.py:306] [psm-grpc-client-9b5756c77-4gv6d] xds channel: <Channel channel_id=10 target=trafficdirector.googleapis.com:443 call_started=7 calls_failed=7 state=READY>
I1010 22:54:19.386313 140608769881920 client_app.py:306] [psm-grpc-client-9b5756c77-4gv6d] xds channel: <Channel channel_id=10 target=trafficdirector.googleapis.com:443 call_started=8 calls_failed=8 state=READY>
I1010 22:54:35.517963 140608769881920 client_app.py:306] [psm-grpc-client-9b5756c77-4gv6d] xds channel: <Channel channel_id=10 target=trafficdirector.googleapis.com:443 call_started=8 calls_failed=8 state=READY>
I1010 22:55:00.638522 140608769881920 client_app.py:306] [psm-grpc-client-9b5756c77-4gv6d] xds channel: <Channel channel_id=10 target=trafficdirector.googleapis.com:443 call_started=10 calls_failed=8 state=READY>
I1010 22:55:00.638787 140608769881920 client_app.py:314] [psm-grpc-client-9b5756c77-4gv6d] Found an active XDS channel
I1010 22:55:00.638983 140608769881920 client_app.py:288] [psm-grpc-client-9b5756c77-4gv6d] Channel to trafficdirector.googleapis.com:443 transitioned to active
I1010 22:55:00.639290 140608769881920 client_app.py:240] [psm-grpc-client-9b5756c77-4gv6d] Waiting to report a READY channel to xds:///psm-grpc-server:8080
I1010 22:55:00.749331 140608769881920 client_app.py:347] [psm-grpc-client-9b5756c77-4gv6d] Server channel: <Channel channel_id=5 target=xds:///psm-grpc-server:8080 call_started=2215 calls_failed=1753 state=READY>
```
* Error Message when XDS channel check failed:
```
E1010 23:09:15.111581 140016347227968 base_testcase.py:60] ERROR Traceback in __main__.BaselineTest.test_traffic_director_grpc_setup:
Traceback (most recent call last):
File "/usr/local/google/home/xuanwn/workspace/xds/grpc/tools/run_tests/xds_k8s_test_driver/tests/baseline_test.py", line 53, in test_traffic_director_grpc_setup
test_client: _XdsTestClient = self.startTestClient(test_server)
File "/usr/local/google/home/xuanwn/workspace/xds/grpc/tools/run_tests/xds_k8s_test_driver/framework/xds_k8s_testcase.py", line 787, in startTestClient
return self._start_test_client(test_server.xds_uri, **kwargs)
File "/usr/local/google/home/xuanwn/workspace/xds/grpc/tools/run_tests/xds_k8s_test_driver/framework/xds_k8s_testcase.py", line 798, in _start_test_client
test_client.wait_for_active_xds_channel(
File "/usr/local/google/home/xuanwn/workspace/xds/grpc/tools/run_tests/xds_k8s_test_driver/framework/test_app/client_app.py", line 171, in wait_for_active_xds_channel
return self.wait_for_xds_channel_active(
File "/usr/local/google/home/xuanwn/workspace/xds/grpc/tools/run_tests/xds_k8s_test_driver/framework/test_app/client_app.py", line 283, in wait_for_xds_channel_active
channel = retryer(
File "/usr/local/google/home/xuanwn/.pyenv/versions/310xds/lib/python3.10/site-packages/tenacity/__init__.py", line 423, in __call__
do = self.iter(retry_state=retry_state)
File "/usr/local/google/home/xuanwn/.pyenv/versions/310xds/lib/python3.10/site-packages/tenacity/__init__.py", line 369, in iter
return self.retry_error_callback(retry_state=retry_state)
File "/usr/local/google/home/xuanwn/workspace/xds/grpc/tools/run_tests/xds_k8s_test_driver/framework/helpers/retryers.py", line 141, in error_handler
raise RetryError(
framework.helpers.retryers.RetryError: Retry error calling framework.test_app.client_app.XdsTestClient.find_active_xds_channel: timeout 0:05:00 (h:mm:ss) exceeded. Last exception: ChannelNotActive: [psm-grpc-client-755fc5b468-qkh22] Client has no active channel with xds server trafficdirector.googleapis.com:443
```
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---------
Co-authored-by: Sergii Tkachenko <hi@sergii.org>
Xuan Wang
b16fa809e9