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/main.py

@@ -425,13 +425,13 @@ async def lifespan(app: FastAPI):
         log.info('Initializing tool servers...')
         try:
             await set_tool_servers(mock_request)
-            log.info(f'Initialized {len(app.state.TOOL_SERVERS)} tool server(s)')
+            log.info('Initialized %s tool server(s)', len(app.state.TOOL_SERVERS))
         except Exception as e:
             log.warning(f'Failed to initialize tool servers at startup: {e}')
 
         try:
             await set_terminal_servers(mock_request)
-            log.info(f'Initialized {len(app.state.TERMINAL_SERVERS)} terminal server(s)')
+            log.info('Initialized %s terminal server(s)', len(app.state.TERMINAL_SERVERS))
         except Exception as e:
             log.warning(f'Failed to initialize terminal servers at startup: {e}')
 
@@ -2594,7 +2594,7 @@ async def register_client(request, client_id: str) -> bool:
         **apply_connection_oauth_options(connection, oauth_client_info.model_dump(mode='json'))
     )
     oauth_client_manager.add_client(client_id, oauth_client_info)
-    log.info(f'Re-registered OAuth client {client_id} for tool server')
+    log.info('Re-registered OAuth client %s for tool server', client_id)
     return True