Move some vars to globals (#11017)

### What problem does this PR solve?

As title.

### Type of change

- [x] Refactoring

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

agent/tools/retrieval.py

@@ -25,6 +25,7 @@ from api.db.services.dialog_service import meta_filter
 from api.db.services.knowledgebase_service import KnowledgebaseService
 from api.db.services.llm_service import LLMBundle
 from api import settings
+from common import globals
 from common.connection_utils import timeout
 from rag.app.tag import label_question
 from rag.prompts.generator import cross_languages, kb_prompt, gen_meta_filter
@@ -170,7 +171,7 @@ class Retrieval(ToolBase, ABC):
 
         if kbs:
             query = re.sub(r"^user[:：\s]*", "", query, flags=re.IGNORECASE)
-            kbinfos = settings.retriever.retrieval(
+            kbinfos = globals.retriever.retrieval(
                 query,
                 embd_mdl,
                 [kb.tenant_id for kb in kbs],
@@ -186,7 +187,7 @@ class Retrieval(ToolBase, ABC):
             )
             if self._param.toc_enhance:
                 chat_mdl = LLMBundle(self._canvas._tenant_id, LLMType.CHAT)
-                cks = settings.retriever.retrieval_by_toc(query, kbinfos["chunks"], [kb.tenant_id for kb in kbs], chat_mdl, self._param.top_n)
+                cks = globals.retriever.retrieval_by_toc(query, kbinfos["chunks"], [kb.tenant_id for kb in kbs], chat_mdl, self._param.top_n)
                 if cks:
                     kbinfos["chunks"] = cks
             if self._param.use_kg: