Adds a new boolean parameter `expect_success` to the
`add_p2p_connection` method. If set, the node under
test doesn't wait for connection to be established
and is useful for testing scenarios when disconnection
is expected.
Without this parameter, intermittent test failures can happen
if the disconnection happens before wait_until for is_connected
is hit inside `add_p2p_connection`.
Co-Authored-By: Sebastian Falbesoner <sebastian.falbesoner@gmail.com>