Drop [LB Rolling] diagnostic logs back to debug

The bulk rolling-mirror ensure path was instrumented with INFO
lines + a WARNING on SELECT failure (commit 5378b726) while we
chased down why only one rolling mirror was being created — turned
out the issue was simply needing two refresh cycles after the
rolling code shipped. Diagnostic served its purpose, removing
the noise from every LB refresh now.

- Dropped per-walk + per-match + summary INFO lines from
  ``_ensure_rolling_mirrors_from_cache`` — the loop is silent.
- Reverted the outer SELECT failure catch from ``logger.warning``
  back to ``logger.debug``.
- Kept the per-placeholder ``Pre-created rolling mirror
  placeholder`` INFO line in ``_ensure_rolling_series_mirror``
  since it's a genuine one-shot event (only fires when a new
  placeholder is actually inserted, not on every refresh).

core/listenbrainz_manager.py

@@ -245,24 +245,10 @@ class ListenBrainzManager:
                 (self.profile_id,),
             )
             titles = [row[0] for row in cursor.fetchall() if row[0]]
-            logger.info(
-                f"[LB Rolling] Bulk ensure walking {len(titles)} cached titles for profile {self.profile_id}"
-            )
-            from core.playlists.lb_series import detect_series
-            matched = 0
             for title in titles:
-                m = detect_series(title)
-                if m is not None:
-                    matched += 1
-                    logger.info(
-                        f"[LB Rolling] Title matched series: {title!r} -> {m.series_id}"
-                    )
                 self._ensure_rolling_series_mirror(cursor, title)
-            logger.info(
-                f"[LB Rolling] Bulk ensure done — {matched}/{len(titles)} titles matched a series"
-            )
         except Exception as exc:
-            logger.warning(f"Bulk rolling-mirror ensure skipped: {exc}")
+            logger.debug(f"Bulk rolling-mirror ensure skipped: {exc}")
 
     def _ensure_rolling_series_mirror(self, cursor, playlist_title: str):
         """Upsert a placeholder ``mirrored_playlists`` row for the