Allow 0xB error for crash_gen tool, per TD-1648

tests/pytest/crash_gen/crash_gen.py

@@ -1648,6 +1648,7 @@ class Task():
     def _isErrAcceptable(self, errno, msg):
         if errno in [
                 0x05,  # TSDB_CODE_RPC_NOT_READY
+                0x0B,  # Unable to establish connection, more details in TD-1648
                 # 0x200, # invalid SQL， TODO: re-examine with TD-934
                 0x217, # "db not selected", client side defined error code
                 0x218, # "Table does not exist" client side defined error code