chore: add a migration that removes incorrectly set sysuserid

src/migrations/20240125090553-events-fix-incorrectly-assigned-sysuser-id.js

@@ -0,0 +1,16 @@
+exports.up = function (db, cb) {
+  db.runSql(
+      `
+      UPDATE events SET created_by_user_id = null
+      WHERE
+          created_by_user_id = -1337 AND
+          created_by = 'unleash_system_user' OR
+          created_by = '[email protected]';
+      `,
+      cb,
+  );
+};
+
+exports.down = function (db, cb) {
+    cb();
+};