docs: update documentation for 31 day subscription message retention

PiperOrigin-RevId: 673028761

Source-Link: googleapis/googleapis@394f626

Source-Link: googleapis/googleapis-gen@88f68a7
Copy-Tag: eyJwIjoiYXBpcy9Hb29nbGUuQ2xvdWQuUHViU3ViLlYxLy5Pd2xCb3QueWFtbCIsImgiOiI4OGY2OGE3MDI0YjAwZmY3ZTIwNDkxOWE5N2I4N2EzMDA3YjExMjNjIn0=

Author: gcf-owl-bot[bot]

apis/Google.Cloud.PubSub.V1/Google.Cloud.PubSub.V1/Pubsub.g.cs

@@ -5745,7 +5745,7 @@ public bool RetainAckedMessages {
     /// backlog, from the moment a message is published. If `retain_acked_messages`
     /// is true, then this also configures the retention of acknowledged messages,
     /// and thus configures how far back in time a `Seek` can be done. Defaults to
-    /// 7 days. Cannot be more than 7 days or less than 10 minutes.
+    /// 7 days. Cannot be more than 31 days or less than 10 minutes.
     /// </summary>
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
     [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]