sd-device-monitor: unconditionally increase buffer size by sd_device_monitor_new()

As suggested at https://github.com/systemd/systemd/pull/29872#discussion_r1382932633:
> socket memory is these days accounted to the process that owns a socket,
> hence we shouldn't be too concerned that this might waste memory.

src/udev/udev-manager.c

@@ -1225,15 +1225,6 @@ int manager_init(Manager *manager, int fd_ctrl, int fd_uevent) {
         if (r < 0)
                 return log_error_errno(r, "Failed to initialize device monitor: %m");
 
-        /* Bump receiver buffer, but only if we are not called via socket activation, as in that
-         * case systemd sets the receive buffer size for us, and the value in the .socket unit
-         * should take full effect. */
-        if (fd_uevent < 0) {
-                r = sd_device_monitor_set_receive_buffer_size(manager->monitor, 128 * 1024 * 1024);
-                if (r < 0)
-                        log_warning_errno(r, "Failed to set receive buffer size for device monitor, ignoring: %m");
-        }
-
         (void) sd_device_monitor_set_description(manager->monitor, "manager");
 
         r = device_monitor_enable_receiving(manager->monitor);

src/udev/udevadm-monitor.c

@@ -66,8 +66,6 @@ static int setup_monitor(MonitorNetlinkGroup sender, sd_event *event, sd_device_
         if (r < 0)
                 return log_error_errno(r, "Failed to create netlink socket: %m");
 
-        (void) sd_device_monitor_set_receive_buffer_size(monitor, 128*1024*1024);
-
         r = sd_device_monitor_attach_event(monitor, event);
         if (r < 0)
                 return log_error_errno(r, "Failed to attach event: %m");

src/udev/udevadm-trigger.c

@@ -526,8 +526,6 @@ int trigger_main(int argc, char *argv[], void *userdata) {
                 if (r < 0)
                         return log_error_errno(r, "Failed to create device monitor object: %m");
 
-                (void) sd_device_monitor_set_receive_buffer_size(m, 128*1024*1024);
-
                 r = sd_device_monitor_attach_event(m, event);
                 if (r < 0)
                         return log_error_errno(r, "Failed to attach event to device monitor: %m");

src/udev/udevadm-wait.c

@@ -184,8 +184,6 @@ static int setup_monitor(sd_event *event, MonitorNetlinkGroup group, const char
         if (r < 0)
                 return r;
 
-        (void) sd_device_monitor_set_receive_buffer_size(monitor, 128*1024*1024);
-
         r = sd_device_monitor_attach_event(monitor, event);
         if (r < 0)
                 return r;