Remove user_credential_tests from the shared folder (Azure#15427)

Co-authored-by: turalf <tufarhad@microsoft.com>

Author: turalf

…tration/_shared/user_credential_tests.py …istration/tests/user_credential_tests.pysdk/communication/azure-communication-administration/azure/communication/administration/_shared/user_credential_tests.py renamed to sdk/communication/azure-communication-administration/tests/user_credential_tests.py sdk/communication/azure-communication-administration/azure/communication/administration/_shared/user_credential_tests.py renamed to sdk/communication/azure-communication-administration/tests/user_credential_tests.py

@@ -5,8 +5,8 @@
 # --------------------------------------------------------------------------
 from unittest import TestCase
 from unittest.mock import MagicMock
-from .user_credential import CommunicationUserCredential
-from .utils import create_access_token
+from azure.communication.administration._shared.user_credential import CommunicationUserCredential
+from azure.communication.administration._shared.utils import create_access_token
 
 
 class TestCommunicationUserCredential(TestCase):