[Bug] Authorization missing when auditloader plugin redirect stream load

[wyb]

Describe the bug
Auditloader plugin load fe auditlog into doris failed.

fe.log
2020-04-21 11:52:07,544 INFO 36 [DorisStreamLoader.loadBatch():119] AuditLoader plugin load with label: audit_20200321_115207, response code: 200, msg: OK, content: { "TxnId": -1, "Label"
: "audit_20200321_115207", "Status": "Fail", "Message": "no valid Basic authorization", "NumberTotalRows": 0, "NumberLoadedRows": 0, "NumberFilteredRows": 0, "NumberUnselected
Rows": 0, "LoadBytes": 0, "LoadTimeMs": 0}