Forwarding error may cause request not found in request processor pending queue

[JackyWoo]

Change log:

• Add log, for forwarding error may cause request not found in request processor pending queue

2024.02.29 14:16:16.574302 [ 116 ] <Warning> RequestForwarder: Forward request ForwardType: User, session 0x4b8, xid 14265061 timeout
2024.02.29 14:16:16.574338 [ 116 ] <Warning> RequestProcessor: Found error request #0x4b8#14265061#Multi accepted:false error_code:-2
2024.02.29 14:16:16.574709 [ 59 ] <Warning> RequestProcessor: Not found error request #0x4b8#14265061#Multi accepted:false error_code:-2 in pending queue. Possible reason: 1.close requests from deadSessionCleanThread are not put into pending queue; 2.error occurs(forward or append entries) but request is still committed, 'processCommittedRequest' may delete request from pending request first, so here we can not find it. We also delete it from errors.