Attempt fix flake

This test is flaky around the fifth run for some reason. My
guess is because another cleanup process is interfering, which
seems strange but not impossible. Anyway, moving the content-existence
check to _before_ changing its expiration seems to fix the issue.

server/svix-server/tests/it/e2e_message.rs

@@ -395,6 +395,12 @@ async fn test_payload_retention_period() {
         .unwrap();
     let msg_id = msg.id.clone();
 
+    let content: Option<messagecontent::Model> = messagecontent::Entity::find_by_id(msg_id.clone())
+        .one(&pool)
+        .await
+        .unwrap();
+    assert_eq!(content.unwrap().id, msg_id.clone());
+
     let res = messagecontent::Entity::update_many()
         .col_expr(
             messagecontent::Column::Expiration,
@@ -406,12 +412,6 @@ async fn test_payload_retention_period() {
         .unwrap();
     assert_eq!(1, res.rows_affected);
 
-    let content: Option<messagecontent::Model> = messagecontent::Entity::find_by_id(msg_id.clone())
-        .one(&pool)
-        .await
-        .unwrap();
-    assert_eq!(content.unwrap().id, msg_id.clone());
-
     expired_message_cleaner::clean_expired_messages(&pool, 5000, false)
         .await
         .unwrap();