impl-node: remove the leaf node check

This was a hack around some scheduler issues that we should be able to
handle better now.

One of the cases is:

  Source -> (p)pw-record

Which would never work otherwise because pw-record does not activate the
Source and when the Source is activated in any other way, pw-record
would not follow.

This will still fail with the current scheduler, but the leaf check is
not so great because it doesn't work in this case:

  Source -> (p)loopback-in|loopback-out(p) -> Sink

What is probably required is a passive mode that doesn't activate but
does follows the peer.

src/pipewire/impl-node.c

@@ -1325,10 +1325,6 @@ static void check_properties(struct pw_impl_node *node)
 		}
 	}
 	node->lock_rate = pw_properties_get_bool(node->properties, PW_KEY_NODE_LOCK_RATE, false);
-	/* the leaf node is one that only produces/consumes the data. We can deduce this from the
-	 * absence of a link-group and the fact that it has no output/input ports. */
-	node->leaf = node->link_groups == NULL &&
-			(node->info.max_input_ports == 0 || node->info.max_output_ports == 0);
 
 	value = pw_properties_get_uint32(node->properties, PW_KEY_NODE_FORCE_RATE, SPA_ID_INVALID);
 	if (value == 0)

src/pipewire/private.h

@@ -786,7 +786,6 @@ struct pw_impl_node {
 	unsigned int async:1;		/**< async processing, one cycle latency */
 	unsigned int lazy:1;		/**< the graph is lazy scheduling */
 	unsigned int exclusive:1;	/**< ports can only be linked once */
-	unsigned int leaf:1;		/**< node only produces/consumes data */
 	unsigned int reliable:1;	/**< ports need reliable tee */
 
 	uint32_t transport;		/**< latest transport request */