Some waitcondition related tests in heat_tempest_plugins failed in a SSL endpoint used environment.

Issue

• Some waitcondition related tests in heat_tempest_plugins failed in a SSL endpoint used environment.
• My overcloud deployment enables a SSL endpoint for public endpoint. The SSL certificate is self-signed or its CA certificate is not included in an instance image by default.
• The failed tests are

heat_tempest_plugin.tests.functional.test_os_wait_condition.OSWaitCondition.test_create_stack_with_multi_signal_waitcondition
heat_tempest_plugin.tests.scenario.test_server_signal.ServerSignalIntegrationTest.test_server_signal_userdata_format_raw
heat_tempest_plugin.tests.scenario.test_server_signal.ServerSignalIntegrationTest.test_server_signal_userdata_format_software_config