Fix node.py: try_shutdown and cleanup (#145)

testgres/node.py

@@ -351,7 +351,7 @@ def _try_shutdown(self, max_attempts, with_force=False):
             # If force stopping is enabled and PID is valid
             if with_force and node_pid != 0:
                 # If we couldn't stop the node
-                p_status_output = self.os_ops.exec_command(cmd=f'ps -p {node_pid}', shell=True).decode('utf-8')
+                p_status_output = self.os_ops.exec_command(cmd=f'ps -o pid= -p {node_pid}', shell=True, ignore_errors=True).decode('utf-8')
                 if self.status() != NodeStatus.Stopped and p_status_output and str(node_pid) in p_status_output:
                     try:
                         eprint(f'Force stopping node {self.name} with PID {node_pid}')