Fix getting exit code on capsule tunnel error (#14821)

(cherry picked from commit 625017b)

robottelo/host_helpers/satellite_mixins.py

@@ -288,10 +288,10 @@ def default_url_on_new_port(self, oldport, newport):
             post_ncat_procs = self.execute('pgrep ncat').stdout.splitlines()
             ncat_pid = set(post_ncat_procs).difference(set(pre_ncat_procs))
             if not len(ncat_pid):
-                stderr = channel.get_exit_status()[1]
-                logger.debug(f'Tunnel failed: {stderr}')
+                err = channel.get_exit_signal()
+                logger.debug(f'Tunnel failed: {err}')
                 # Something failed, so raise an exception.
-                raise CapsuleTunnelError(f'Starting ncat failed: {stderr}')
+                raise CapsuleTunnelError(f'Starting ncat failed: {err}')
             forward_url = f'https://{self.hostname}:{newport}'
             logger.debug(f'Yielding capsule forward port url: {forward_url}')
             try: