Use MyBackendType in more places to check what process this is
Remove IsBackgroundWorker, IsAutoVacuumLauncherProcess(),
IsAutoVacuumWorkerProcess(), and IsLogicalSlotSyncWorker() in favor of
new Am*Process() macros that use MyBackendType. For consistency with
the existing Am*Process() macros.
Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/
f3ecd4cb-85ee-4e54-8278-
5fabfb3a4ed0@iki.fi