Fix error and format issue (#11975)

### What problem does this PR solve?

1. Fix error of book chunking.
2. Fix format issues.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)
- [x] Refactoring

---------

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

agent/test/dsl_examples/categorize_and_agent_with_tavily.json

@@ -75,7 +75,7 @@
   },
   "history": [],
   "path": [],
-  "retrival": {"chunks": [], "doc_aggs": []},
+  "retrieval": {"chunks": [], "doc_aggs": []},
   "globals": {
     "sys.query": "",
     "sys.user_id": "",

agent/test/dsl_examples/iteration.json

@@ -82,7 +82,7 @@
   },
   "history": [],
   "path": [],
-  "retrival": {"chunks": [], "doc_aggs": []},
+  "retrieval": {"chunks": [], "doc_aggs": []},
   "globals": {
     "sys.query": "",
     "sys.user_id": "",

agent/test/dsl_examples/retrieval_and_generate.json

@@ -51,7 +51,7 @@
   },
   "history": [],
   "path": [],
-  "retrival": {"chunks": [], "doc_aggs": []},
+  "retrieval": {"chunks": [], "doc_aggs": []},
   "globals": {
     "sys.query": "",
     "sys.user_id": "",

agent/test/dsl_examples/retrieval_categorize_and_generate.json

@@ -85,7 +85,7 @@
   },
   "history": [],
   "path": [],
-  "retrival": {"chunks": [], "doc_aggs": []},
+  "retrieval": {"chunks": [], "doc_aggs": []},
   "globals": {
     "sys.query": "",
     "sys.user_id": "",

agent/test/dsl_examples/tavily_and_generate.json

@@ -45,7 +45,7 @@
   },
   "history": [],
   "path": [],
-  "retrival": {"chunks": [], "doc_aggs": []},
+  "retrieval": {"chunks": [], "doc_aggs": []},
   "globals": {
     "sys.query": "",
     "sys.user_id": "",