refactor(localdb): one replication predicate shared by table registration and the alarm drain gate (#603)

The drain gate counted SyncListenPort; a port with no ApiKey shares nothing (fail-closed
passive endpoint), and an ApiKey-only passive node shares its queue but was never gated.

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

src/Server/ZB.MOM.WW.OtOpcUa.Host/Configuration/LocalDbSetup.cs

@@ -170,12 +170,9 @@ public static class LocalDbSetup
     /// <returns><c>true</c> when this node is configured to replicate.</returns>
     public static bool ReplicationIsConfigured(IConfiguration configuration)
     {
-        ArgumentNullException.ThrowIfNull(configuration);
-
-        var section = configuration.GetSection(LocalDbRegistration.ReplicationSectionPath);
-
-        return !string.IsNullOrWhiteSpace(section["PeerAddress"])
-            || !string.IsNullOrWhiteSpace(section["ApiKey"]);
+        // Shared with the alarm-historian drain gate (#603): one predicate, so the nodes that capture
+        // changes and the nodes that stand down for a peer can never disagree.
+        return Runtime.LocalDbReplicationPolicy.IsConfigured(configuration);
     }
 
     /// <summary>Opts every replicated table into change capture, baselining what is already there.</summary>