jack: use node.passive to make passive links

Let the node.passive property make passive links. PIPEWIRE_LINK_PASSIVE
overrides the node property.

Add some nice tweaks for qsynth so that it suspends and fades out
nicely by default.

src/daemon/jack.conf.in

@@ -104,15 +104,22 @@ jack.rules = [
             }
         }
     }
-    {
-        matches = [
-            {
-                application.process.binary = "jack_bufsize"
-            }
+    { matches = [
+            { application.process.binary = "jack_bufsize" }
         ]
         actions = {
             update-props = {
-                jack.global-buffer-size = true
+                jack.global-buffer-size = true   # quantum set globally using metadata
+            }
+        }
+    }
+    { matches = [
+            { application.process.binary = "qsynth" }
+        ]
+        actions = {
+            update-props = {
+                node.pause-on-idle = false  # makes audio fade out when idle
+                node.passive = true         # makes the sink and qsynth suspend
             }
         }
     }