pattern: Make lister flush regularly origins to scheduler

As origins is a generator, the previous behavior would try to consume the overall
generator to send the records.

This groups and sends batch of 100 origins to the scheduler for writing.

Related to T3003

swh/lister/pattern.py

@@ -7,6 +7,7 @@ from dataclasses import dataclass
 from typing import Any, Dict, Generic, Iterable, Iterator, List, Optional, TypeVar
 
 from swh.core.config import load_from_envvar
+from swh.core.utils import grouper
 from swh.scheduler import get_scheduler, model
 from swh.scheduler.interface import SchedulerInterface
 
@@ -221,8 +222,12 @@ class Lister(Generic[StateType, PageType]):
         Returns:
           the number of listed origins recorded in the scheduler
         """
-        ret = self.scheduler.record_listed_origins(origins)
-        return len(ret)
+        count = 0
+        for batch_origins in grouper(origins, n=100):
+            ret = self.scheduler.record_listed_origins(batch_origins)
+            count += len(ret)
+
+        return count
 
     @classmethod
     def from_config(cls, scheduler: Dict[str, Any], **config: Any):