core/manager: kill unused default_unit_job_id field

While at it, make sure the "Queued ... job for default target"
message is always logged, i.e. also when we fall back to
start job instead of isolate.

src/core/main.c

@@ -2639,12 +2639,10 @@ static int do_queue_default_job(
                 return log_struct_errno(LOG_EMERG, r,
                                         LOG_MESSAGE("Failed to isolate default target: %s", bus_error_message(&error, r)),
                                         LOG_MESSAGE_ID(SD_MESSAGE_CORE_ISOLATE_TARGET_FAILED_STR));
-        } else
-                log_info("Queued %s job for default target %s.",
-                         job_type_to_string(job->type),
-                         unit_status_string(job->unit, NULL));
+        }
 
-        m->default_unit_job_id = job->id;
+        log_info("Queued %s job for default target %s.",
+                 job_type_to_string(job->type), unit_status_string(job->unit, NULL));
 
         return 0;
 }

src/core/manager.h

@@ -324,7 +324,6 @@ typedef struct Manager {
         bool send_reloading_done;
 
         uint32_t current_job_id;
-        uint32_t default_unit_job_id;
 
         /* Data specific to the Automount subsystem */
         int dev_autofs_fd;