Increase context deadline for TestTaskQueueAPIRateLimitOverridesWorkerLimit (temporalio#8696)

## What changed?
Increase flakiness buffer for
TestTaskQueueAPIRateLimitOverridesWorkerLimit

## Why?
It was still flaky at 3.5s

## How did you test it?
- [ ] built
- [ ] run locally and tested manually
- [ ] covered by existing tests
- [ ] added new unit test(s)
- [ ] added new functional test(s)

## Potential risks
Increasing the flakiness buffer too far could eventually mean this test
is worthless. I think 5s is ok though and still tests the rough shape of
the API.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Increase buffer/timeout for the task-queue API rate-limit test and
adapt chasm parent-pointer test to Get() no-error API.
> 
> - **Tests**:
> - **Task queue rate limiting**
(`tests/TaskQueueSuite.TestTaskQueueAPIRateLimitOverridesWorkerLimit`):
> - Increase flakiness buffer to `3.75s` and extend `drainTimeout` to
`30s`.
>     - Add notes explaining increased buffer/timeout due to flakiness.
>   - **Chasm tree tests** (`chasm/tree_test.go`):
> - Update `assertParentPointer` to use `Get(chasmContext)` without
error returns for `SubComponent1` and `SubComponent11`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
f876389. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: carlydf

tests/task_queue_test.go

@@ -261,11 +261,15 @@ func (s *TaskQueueSuite) configureRateLimitAndLaunchWorkflows(
 // The first five activities should run immediately, and the rest should be throttled to 5 RPS.
 // The test verifies that the total time taken for all activities to complete is within the expected range
 // To avoid test flakiness, the test uses a buffer of 1 second for the expected total time.
+// Note: The flakiness buffer has since been increased to 3.5s, but it was still flaky (err context deadline exceeded),
+// so I now increased it to 3.75s and increasing the context deadline. If the buffer is >=4s, the test stops
+// testing anything because the test will succeed even if all the activities complete immediately as if there were no rate limit.
+// TODO(matching team): Possibly rewrite test if this issue persists.
 func (s *TaskQueueSuite) TestTaskQueueAPIRateLimitOverridesWorkerLimit() {
 	const (
 		apiRPS            = 5.0
 		taskCount         = 25
-		buffer            = time.Duration(3.5 * float64(time.Second)) // High Buffer to account for test flakiness
+		buffer            = time.Duration(3.75 * float64(time.Second)) // High Buffer to account for test flakiness
 		activityTaskQueue = "RateLimitTest"
 	)
 	expectedTotal := time.Duration(float64(taskCount-int(apiRPS))/apiRPS) * time.Second
@@ -283,7 +287,8 @@ func (s *TaskQueueSuite) TestTaskQueueAPIRateLimitOverridesWorkerLimit() {
 		workerRPS = 50.0
 		// Test typically completes in ~6.2 seconds on average.
 		// Timeout is set to 10s to reduce flakiness.
-		drainTimeout = 10 * time.Second
+		// Note: Flaked at 10s, so trying 30s.
+		drainTimeout = 30 * time.Second
 		activityName = "trackableActivity"
 	)