CBG-5557: fix TestReplicationStatusActions flake

[torcolvin]

CBG-5557: fix TestReplicationStatusActions flake

After action=reset, the sgReplicateManager goroutine calls alignState(ctx, resetting) on the local ActiveReplicator, which clears the checkpoint (c.Checkpointer = nil) and removes the persisted status document. At this point the in-memory replicator reports status=stopped and LastSeqPull="". The test's EventuallyWithT saw both conditions satisfied and proceeded to call action=start.

However, the manager hadn't yet called UpdateReplicationState(id, stopped) to persist TargetState=stopped back to the cluster config. That call happens synchronously after alignState returns, but there is a window between the two where TargetState is still "resetting" in the cluster config. UpdateReplicationState (called by action=start) reads the cluster config and passes TargetState to isValidStateChange, which rejects the "resetting -> running" transition with a 400.

[Copilot]

Pull request overview

This PR addresses a test flake in Sync Gateway’s sg-replicate status-action flow by ensuring the test waits not only for the in-memory replication status to be reset/stopped, but also for the persisted replication config’s TargetState to be updated back to stopped before issuing a subsequent start action.

Changes:

• Improve failure attribution in test helpers by marking key assertion/wait helper functions as t.Helper().
• Harden TestReplicationStatusActions by additionally waiting until the replication config in /_replication/ reflects TargetState=stopped after a reset.
• Add a lightweight guard/assertion that the replication config entry exists before checking TargetState.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
rest/utilities_testing.go	Marks RequireStatus/AssertStatus as helpers to improve test failure line reporting.
rest/utilities_testing_resttester.go	Marks several RestTester helper methods as helpers for clearer stack traces in failing tests.
rest/replicatortest/replicator_test.go	Extends the reset verification in TestReplicationStatusActions to also wait for persisted TargetState to become stopped, closing the flake window.