Bump trio `echoserver` cancel timeout 1→4s

Same trio 0.29 → 0.33 cancel-cascade slowdown that hit
`test_nested_multierrors` (ea67f1b6) — bumps the
`trio`-backend (non-debug, non-forking) budget in
`test_echoserver_detailed_mechanics` from 1s → 4s.

- The 1s budget raced the ~1s teardown deadline. On a
  deadline-fire trio 0.33 injects
  `Cancelled(source='deadline')` (cancel-reason
  metadata) that wraps the mid-stream KBI in a
  `BaseExceptionGroup`, breaking the bare
  `pytest.raises(KeyboardInterrupt)` below.
- Bump matches the forking-spawner branch (4s).
- Inline NOTE references the tracking issue
  `ai/conc-anal/trio_033_cancel_cascade_slowdown_depth3_issue.md`.

(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code

(cherry picked from commit d7da502d93)

tests/test_infected_asyncio.py

@@ -860,7 +860,14 @@ def test_echoserver_detailed_mechanics(
     timeout: float = (
         999 if tractor.debug_mode()
         else 4 if is_forking_spawner
-        else 1
+        # was 1; the `trio` 0.29 -> 0.33 bump slowed the
+        # cancel-cascade so a 1s budget raced the ~1s teardown
+        # deadline. On a deadline-fire the injected
+        # `Cancelled(source='deadline')` wraps the mid-stream
+        # KBI in a `BaseExceptionGroup`, breaking the bare
+        # `pytest.raises(KeyboardInterrupt)` below. See
+        # `ai/conc-anal/trio_033_cancel_cascade_slowdown_depth3_issue.md`.
+        else 4
     )
 
     # body factored out so the `fail_after_w_trace`-wrapping