test(take-over): hold a displaced attach's "taken over" line until its exit too

changelog.d/integration-flake-take-over-recovery.md

@@ -1,4 +1,3 @@
 ### Maintenance
-- The take-over integration test for an ordinary failed attach now holds its first bytes long
-  enough that a busy runner never takes the failing attempt's last line for an attach before its
-  exit arrives.
+- Two take-over integration tests lengthen the attach hold, so a busy runner never passes on a
+  failing or displaced attach's last line before its exit arrives.

server/take-over.contract.test.ts

@@ -74,7 +74,9 @@ async function fixture(steps: Step[], attachHoldMs?: number) {
 
 describe("explicit take-over intent", () => {
   it("consumes a click when the running ordinary retry succeeds, before later displacement", async () => {
-    const f = await fixture([{ kind: "held" }, { kind: "real", gate: "attach" }, { kind: "held" }]);
+    // displaced, the attach prints herdr's "taken over" and then exits: a hold far longer than that
+    // exit keeps a busy runner from passing the line on before the exit comes
+    const f = await fixture([{ kind: "held" }, { kind: "real", gate: "attach" }, { kind: "held" }], 2_000);
     await until(() => f.starts().length === 2, "ordinary retry held at its gate");
     f.send({ type: "take-over", pane_id: f.paneId });
     await f.barrier();