fix: repair two broken logging calls, one of which makes VECTOR_DB=opengauss unusable (#27838)

SRC_LOG_LEVELS became an empty dict when per-module log levels were dropped, and env.py keeps it only as a legacy name. opengauss.py is the last thing in the tree that still indexes it, at module scope, so importing the module raises KeyError: 'RAG' and any deployment on VECTOR_DB=opengauss dies the first time it touches the vector store. The factory imports it lazily, which is why nothing else trips over it. Deleting the line is the whole fix: every other vector backend takes getLogger(__name__) and inherits the root level.

colbert.py passes an argument to a message with no placeholder to consume it:

    log.info('ColBERT: Loading model', name)

At INFO, which is the default, logging evaluates 'ColBERT: Loading model' % ('colbert-ir/colbertv2.0',) and raises TypeError: not all arguments converted during string formatting. The record is swallowed by handleError, so loading a ColBERT reranker prints '--- Logging error ---' plus a traceback to stderr instead of the model name. Adding %s prints the name and drops the traceback.

backend/open_webui/retrieval/models/colbert.py

@@ -12,7 +12,7 @@ log = logging.getLogger(__name__)
 
 class ColBERT(BaseReranker):
     def __init__(self, name, **kwargs) -> None:
-        log.info('ColBERT: Loading model', name)
+        log.info('ColBERT: Loading model %s', name)
         self.device = 'cuda' if torch.cuda.is_available() else 'cpu'
 
         DOCKER = kwargs.get('env') == 'docker'