[Bug]: Zero width cause search failure for iterator

[MrPresent-Han]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

related: milvus-io/milvus#29305

Expected Behavior

No response

Steps/Code To Reproduce behavior

currently, width may be zero when the last page has results with completely same distances, which may lead to failure on the next iteration.

Environment details

- Hardware/Softward conditions (OS, CPU, GPU, Memory):
- Method of installation (Docker, or from source):
- Milvus version (v0.3.1, or v0.4.0):
- Milvus configuration (Settings you made in `server_config.yaml`):

Anything else?

No response

[XuanYang-cn]

@MrPresent-Han please cherry pick to 2.3 branch