perf: build info log messages lazily so raising the log level actually saves work (#27837)

Raising GLOBAL_LOG_LEVEL to WARNING buys quieter output but not less work: 241 INFO call sites interpolate their payload into an f-string before the logging call gets to drop it. The heaviest is get_doc, which logs every chunk id and metadata dict in a collection, so on the full-context retrieval path that is the entire knowledge base, once per chat request.

That one line at WARNING, CPython 3.12:

| knowledge base | payload | before   | after   |
| -------------- | ------- | -------- | ------- |
| top-k of 3     | 1.2 kB  | 3.8 us   | 0.07 us |
| 500 chunks     | 201 kB  | 583.6 us | 0.08 us |
| 5000 chunks    | 2.0 MB  | 5.8 ms   | 0.15 us |

The lazy form log.info('query_doc:result %s %s', result.ids, result.metadatas) hands the payload to record.getMessage(), which the InterceptHandler only reaches once a record has passed the level check. Output at INFO is byte-identical. Two sites that already built their message eagerly, one str concat and one % operator, move to the same lazy form.

backend/open_webui/utils/automations.py

@@ -211,8 +211,9 @@ async def scheduler_worker_loop(app) -> None:
     SCHEDULER_POLL_INTERVAL env var (default: 10 seconds).
     """
     log.info(
-        f'Scheduler worker started (timer poll interval: {TIMER_POLL_INTERVAL}s, '
-        f'scheduler poll interval: {SCHEDULER_POLL_INTERVAL}s)'
+        'Scheduler worker started (timer poll interval: %ss, scheduler poll interval: %ss)',
+        TIMER_POLL_INTERVAL,
+        SCHEDULER_POLL_INTERVAL,
     )
     next_scheduler_poll = 0.0
 
@@ -240,7 +241,7 @@ async def scheduler_worker_loop(app) -> None:
                     async with get_async_db() as db:
                         batch = await Automations.claim_due(int(time.time_ns()), limit=10, db=db)
                     if batch:
-                        log.info(f'Claimed {len(batch)} due automation(s)')
+                        log.info('Claimed %s due automation(s)', len(batch))
                     for automation in batch:
                         asyncio.create_task(execute_automation(app, automation))
                 except Exception: