Skip location overlap validation when namespace location is unchanged

[ayushtkn]

updateNamespaceProperties runs the sibling location-overlap validation on every namespace property update, even when the update leaves the namespace location untouched.

That check scales with the number of sibling tables and namespaces, so a trivial update such as setting owner can do a significant amount of work purely to verify a base location that did not change. This change gates the check on the location actually changing, which is how the table and view commit paths already gate the same validation, and leaves behaviour identical whenever the location is modified.

Checklist

• 🛡️ Don't disclose security issues! (contact security@apache.org)
• 🔗 Clearly explained why the changes are needed, or linked related issues: Fixes #
• 🧪 Added/updated tests with good coverage, or manually tested (and explained how)
• 💡 Added comments for complex logic
• 🧾 Updated CHANGELOG.md (if needed)
• 📚 Updated documentation in site/content/in-dev/unreleased (if needed)

[Copilot]

Pull request overview

This PR reduces unnecessary work when updating namespace properties by skipping sibling location-overlap validation unless the namespace location actually changes, aligning namespace updates with the existing table/view validation behavior.

Changes:

• Gate namespace sibling location-overlap validation in LocalIcebergCatalog#setProperties on whether the namespace base location changed.
• Add a regression test that asserts overlap validation work (via metastore listEntities calls) is performed only when location is updated.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
runtime/service/src/main/java/org/apache/polaris/service/catalog/iceberg/LocalIcebergCatalog.java	Skips location-overlap validation on namespace property updates when the base location is unchanged.
runtime/service/src/test/java/org/apache/polaris/service/catalog/iceberg/IcebergAllowedLocationTest.java	Adds a test to verify overlap validation is triggered only on namespace location changes.

[vigneshio]

LGTM...

nits: missing / in the namespace location format string, and the listEntities spy may be brittle if OPTIMIZED_SIBLING_CHECK is on - consider pinning it false... WDYT ??