fix: adjust cases.task to start test_node.sh to first case because its time is uncertain

tests/parallel_test/cases.task

 # 20,,pytest,python3 insert/retentionpolicy.py change date time
+500,,docs-examples-test,./test_node.sh
 299,,pytest,python3 test.py -f update/merge_commit_data-0.py 
 290,,pytest,python3 test.py -f update/merge_commit_data.py 
 241,,pytest,python3 test.py -f update/merge_commit_data2.py 
@@ -593,7 +594,6 @@
 8,,develop-test,python3 ./test.py -f 5-taos-tools/taosdump/taosdumpTestTypeInt.py 
 8,,develop-test,python3 ./test.py -f 5-taos-tools/taosdump/taosdumpTestTypeDouble.py 
 8,,pytest,python3 test.py -f update/update2.py
-7,,docs-examples-test,./test_node.sh
 7,,system-test,python3 ./test.py -f 5-taos-tools/taosbenchmark/taosdemoTestInsertWithJsonSml-otherPara.py 
 7,,pytest,python3 test.py -f tools/taosdumpTest2.py 
 7,,pytest,python3 test.py -f tools/taosdemoTestdatatype.py