Update Iceberg version to 1.6.1 in tests

[flyrain]

Description

We have upgraded to Iceberg 1.6.1 in the dependency. We should update it in integration tests as well.

Type of change

• [x] Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Local test passed

Checklist:

• [x] I have performed a self-review of my code