tree-wide: install matches asynchronously

Let's remove a number of synchronization points from our service
startups: let's drop synchronous match installation, and let's opt for
asynchronous instead.

Also, let's use sd_bus_match_signal() instead of sd_bus_add_match()
where we can.

src/systemctl/systemctl.c

@@ -2905,7 +2905,6 @@ static int start_unit_one(
 
         if (wait_context) {
                 _cleanup_free_ char *unit_path = NULL;
-                const char* mt;
 
                 log_debug("Watching for property changes of %s", name);
                 r = sd_bus_call_method(
@@ -2928,13 +2927,15 @@ static int start_unit_one(
                 if (r < 0)
                         return log_error_errno(r, "Failed to add unit path %s to set: %m", unit_path);
 
-                mt = strjoina("type='signal',"
-                              "interface='org.freedesktop.DBus.Properties',"
-                              "path='", unit_path, "',"
-                              "member='PropertiesChanged'");
-                r = sd_bus_add_match(bus, &wait_context->match, mt, on_properties_changed, wait_context);
+                r = sd_bus_match_signal_async(bus,
+                                              &wait_context->match,
+                                              NULL,
+                                              unit_path,
+                                              "org.freedesktop.DBus.Properties",
+                                              "PropertiesChanged",
+                                              on_properties_changed, NULL, wait_context);
                 if (r < 0)
-                        return log_error_errno(r, "Failed to add match for PropertiesChanged signal: %m");
+                        return log_error_errno(r, "Failed to request match for PropertiesChanged signal: %m");
         }
 
         log_debug("%s manager for %s on %s, %s",