add approval for _enable_legacy_dygraph in unittest (#42687)

* add approval for eager CI

* add wiki manual

tools/check_file_diff_approvals.sh

@@ -391,6 +391,22 @@ if [ "${UNITTEST_FILE_CHANGED}" != "" ] && [ "${GIT_PR_ID}" != "" ]; then
     fi
 fi
 
+if [ "${UNITTEST_FILE_CHANGED}" != "" ] && [ "${GIT_PR_ID}" != "" ]; then
+    ERROR_LINES=""
+    for TEST_FILE in ${UNITTEST_FILE_CHANGED};
+    do
+        ENABLE_LEGACY_DYGRAPH_CI=`git diff -U0 upstream/$BRANCH ${PADDLE_ROOT}/${TEST_FILE} |grep "_enable_legacy_dygraph" || true`
+        if [ "${ENABLE_LEGACY_DYGRAPH_CI}" != "" ]; then
+            ERROR_LINES="${ERROR_LINES}\n${TEST_FILE}\n${ENABLE_LEGACY_DYGRAPH_CI}\n"
+        fi
+    done
+    if [ "${ERROR_LINES}" != "" ]; then
+        ERROR_LINES=${ERROR_LINES//+/'\n+\t'}
+        echo_line="_enable_legacy_dygraph forces the mode to old dynamic graph. You must have one RD (pangyoki (Recommend), Aurelius84 or JiabinYang) approval for the usage (either add or delete) of _enable_legacy_dygraph. For more information, please refer to: https://github.com/PaddlePaddle/Paddle/wiki/Enable-Eager-Mode-in-Paddle-CI. The corresponding lines are as follows:\n${ERROR_LINES}\n"
+        check_approval 1 26408901 9301846 22361972
+    fi
+fi
+
 RUNTYPE_FILE_CHANGED=`git diff --name-only --diff-filter=AM upstream/$BRANCH|grep -E "CMakeLists.txt"||true`
 if [ "${RUNTYPE_FILE_CHANGED}" != "" ] && [ "${GIT_PR_ID}" != "" ]; then
     for CMAKELISTS_FILE in ${RUNTYPE_FILE_CHANGED};