connection manager HTTP/2 tests crashes on OpenBSD

### Describe the bug

```
The following tests FAILED:
600 - connection_manager_single_http2_connection (SEGFAULT)
602 - connection_manager_single_http2_connection_with_settings (SEGFAULT)
604 - connection_manager_many_http2_connections (SEGFAULT)
```
The CI catches couple crash from openBSD, all related to connection manager with HTTP/2.

https://github.com/awslabs/aws-c-http/actions/runs/16332889023/job/46139186189?pr=524

We will need to look into this. https://github.com/awslabs/aws-c-http/pull/524

### Regression Issue

- [ ] Select this option if this issue appears to be a regression.

### Expected Behavior

Don't segfault

### Current Behavior

Segfault without trace back.

### Reproduction Steps

https://github.com/awslabs/aws-c-http/pull/524 This branch adds the CI for those platform.

But we may need to get an openBSD somewhere to reproduce the issue.

### Possible Solution

_No response_

### Additional Information/Context

_No response_

### aws-c-http version used

latest

### Compiler and version used

gcc

### Operating System and version

openbsd

Start with the three failing connection manager HTTP/2 tests: connection_manager_single_http2_connection, connection_manager_single_http2_connection_with_settings, and connection_manager_many_http2_connections. Use the OpenBSD CI job and PR #524 as the reproduction path, then investigate the segfault without a backtrace. Done means all three tests complete without crashing on OpenBSD.

Written by the indexing model from the issue text.