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/models/chats.py

@@ -1935,7 +1935,7 @@ class ChatTable:
             result = await session.execute(stmt)
             all_chats = result.scalars().all()
 
-            log.info(f'The number of chats: {len(all_chats)}')
+            log.info('The number of chats: %s', len(all_chats))
 
             # Validate and return chats
             return [ChatModel.model_validate(chat) for chat in all_chats]
@@ -2100,7 +2100,7 @@ class ChatTable:
 
             bind = await session.connection()
             dialect_name = bind.dialect.name
-            log.info(f'DB dialect name: {dialect_name}')
+            log.info('DB dialect name: %s', dialect_name)
             if dialect_name == 'sqlite':
                 stmt = stmt.filter(
                     text(f"EXISTS (SELECT 1 FROM json_each(Chat.meta, '$.tags') WHERE json_each.value = :tag_id)")
@@ -2227,7 +2227,7 @@ class ChatTable:
             result = await session.execute(stmt.where(Chat.meta['internal'].as_boolean().is_not(True)))
             count = result.scalar()
 
-            log.info(f"Count of chats for folder '{folder_id}': {count}")
+            log.info("Count of chats for folder '%s': %s", folder_id, count)
             return count
 
     async def count_chats_by_folder_ids_and_user_id(
@@ -2241,7 +2241,7 @@ class ChatTable:
             result = await session.execute(stmt.where(Chat.meta['internal'].as_boolean().is_not(True)))
             count = result.scalar()
 
-            log.info(f"Count of chats for folders '{folder_ids}': {count}")
+            log.info("Count of chats for folders '%s': %s", folder_ids, count)
             return count
 
     async def delete_tag_by_id_and_user_id_and_tag_name(