syncthing: let launchd handle restarts.

The alternative is to get into fun restart races between launchd and
syncthing itself.

STNORESTART Do not attempt to restart when requested to, instead just
exit. Set this variable when running under a service manager such as
runit, launchd, etc.
syncthing: update 0.9.14 bottle.

Closes #32273.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>