Make the shell command safer in at least two ways

Prevent errors where we could not retrieve the command status like

  File "/usr/lib/python3.13/site-packages/avocado_spawner_remote/__init__.py", line 218, in wait_task
    if not RemoteSpawner.is_task_alive(runtime_task):
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^

  File "/usr/lib/python3.13/site-packages/avocado_spawner_remote/__init__.py", line 142, in is_task_alive
    status, output = session.cmd_status_output(
                     ~~~~~~~~~~~~~~~~~~~~~~~~~^
        f"pgrep -r R,S -f {runtime_task.task.identifier}"
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^

  File "/usr/lib/python3.13/site-packages/aexpect/client.py", line 1491, in cmd_status_output
    raise ShellStatusError(cmd, out) from error

Use the "safe" flag to handle cases where the shell prompt might be
polluted with "[Done] some-background-process" appearing from the
detached avocado task process but also handle any further unexpected
status retrieval errors. There were still rare cases where the safe
flag might miss something yet it does filter our most cases from
needing to catch status errors (which is also worst in terms of
peformance compared to a regular boolean check).

Signed-off-by: Plamen Dimitrov <plamen.dimitrov@intra2net.com>

Author: pevogam

optional_plugins/spawner_remote/avocado_spawner_remote/__init__.py

@@ -80,11 +80,13 @@ def is_operational(self):
     @staticmethod
     def run_remote_cmd(session, command, timeout):
         try:
-            status, output = session.cmd_status_output(command, timeout)
+            status, output = session.cmd_status_output(command, timeout, safe=True)
         except exceptions.ShellTimeoutError:
             status, output = 2, f"Remote command timeout of {timeout} reached"
         except exceptions.ShellProcessTerminatedError:
             status, output = 2, "Remote command terminated prematurely"
+        except exceptions.ShellStatusError:
+            status, output = 3, f"Remote command could not retrieve status"
         return status, output
 
     @contextlib.contextmanager