RCBC-543: Add consistency helper for update_collection tests

[DemetrisChr]

The collection settings update happens asynchronously across the cluster. This results in update_collection intermittently failing on CI. This change adds a consistency helper for ensuring that the settings have been updated across all nodes, similar to what we have for creating and dropping collections.

[Copilot]

Pull request overview

Adds a new consistency helper to reduce CI flakiness in update_collection tests by waiting until updated collection settings are visible across all cluster nodes.

Changes:

• Introduce wait_until_collection_satisfies_predicate in the test consistency helper to wait on arbitrary collection-state predicates across nodes.
• Use the new helper in collection_manager_test after update_collection calls (history retention and max expiry cases).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
test/utils/consistency_helper.rb	Adds a generic “wait until collection matches predicate” helper using the management /scopes endpoint across all management nodes.
test/collection_manager_test.rb	Updates update_collection tests to wait for cluster-wide propagation before asserting on collection settings.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.