[3.6] bpo-32676, test_asyncio: Fix warning in test_error_in_call_soon() (GH-7462...

[3.6] bpo-32676, test_asyncio: Fix warning in test_error_in_call_soon() (GH-7462) (GH-7483)

* bpo-32676, test_asyncio: Fix warning in test_error_in_call_soon() (GH-7462)

Fix "<CoroWrapper ...> was never yielded from" warning in
PyTask_PyFuture_Tests.test_error_in_call_soon() of
test_asyncio.test_tasks.

Close manually the coroutine on error.

(cherry picked from commit 9f04f0df6fdb27190690bda949d213893d14e807)

* Hide a warning in test_asyncio test_cancel_handshake()

SslProtoHandshakeTests.test_cancel_handshake() of
test_asyncio.test_sslproto: hide a traceback about SSL handshake
failure.