core/service: do not propagate reload for combined RELOADING=1 + READY=1 when notify...

core/service: do not propagate reload for combined RELOADING=1 + READY=1 when notify-reload

Follow-up for 3bd28bf721dc70722ff1c675026ed0b44ad968a3

SERVICE_RELOAD_SIGNAL state can only be reached via explicit reload jobs,
and we have a clear distinction between that and plain RELOADING=1
notifications, the latter of which is issued by clients doing reload
outside of our job engine. I.e. upon SERVICE_RELOAD_SIGNAL + RELOADING=1
we don't propagate reload jobs again, since that's done during transaction
construction stage already. The handling of combined RELOADING=1 + READY=1
so far is bogus however, as it tries to propagate duplicate reload jobs.
Amend this by following the logic for standalone RELOADING=1.