samples: sysbuild: hello_world: Skip test if no second UART

If a second UART was not configured in the hardware map, then skip
the testcase instead of failing.

Signed-off-by: Grzegorz Chwierut <grzegorz.chwierut@nordicsemi.no>

samples/sysbuild/hello_world/pytest/test_both_uart.py

@@ -3,6 +3,7 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 #
+import pytest
 from twister_harness import DeviceAdapter
 
 timeout = 5
@@ -16,4 +17,7 @@ def test_uart_in_app(dut: DeviceAdapter):
 
 def test_uart_in_second_core(dut: DeviceAdapter):
     """Verify logs from uart in second core"""
+    if len(dut.connections) < 2:
+        pytest.skip("Only one UART connection configured for this device")
+
     dut.readlines_until(connection_index=1, regex=regex, print_output=True, timeout=timeout)