Cannot set `write.data.path` to a subdirectory under the current table location OPTIMIZED_SIBLING_CHECK=true

[HonahX]

Describe the bug

Currently, when updating write.data.path of the table to a subdir under the table location, it will fail the location overlap check. This seems to be a regression since https://github.com/apache/polaris/pull/1686/changes#diff-1e0bdc1f194df7cceed5d4b2ddad483199b80d090a1c682f92ecf5fec5f83b2f

To Reproduce

For example

spark-sql> ALTER TABLE tb1 SET TBLPROPERTIES (
  'write.data.path' = '<tableLocation>/alternative_data'
);

org.apache.iceberg.exceptions.ForbiddenException: Forbidden: Unable to create table at location 's3://<table_location>' because it conflicts with existing table or namespace at location 's3://<table_location>`

Actual Behavior

No response

Expected Behavior

The validateNoLocationOverlap should only prevent updating table location to be the same or child of sibling table's locations, not itself. Setting write.data.path to <table_location>/alternative instead of the default <table_location>/data should be a valid use case

Additional context

The issue exists in both the active validateNoLocationOverlap path and the OPTIMIZED_SIBLING_CHECK path. The later have some other issues as described here: #3378

System information

No response

[HonahX]

The issue will still appear when ALLOW_OPTIMIZED_SIBLING_CHECK=true and OPTIMIZED_SIBLING_CHECK=true. The current fix is for the default code path

[github-actions]

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