sample.callstack failing sometimes on x86-32 on ubuntu22 GA CI

https://github.com/DynamoRIO/dynamorio/actions/runs/14001557078/job/39208835327?pr=7391
```
249: wrapping /usr/lib32/libc.so.6!malloc
249: malloc called from:
249: libc.so.6!
249: libc.so.6!
249: @0x8890ff00
249: @0x00000004
249: ld-linux.so.2!
249: @0x00010101
249:
241/379 Test #249: code_api|sample.callstack ........................................***Failed Required regular expression not found. Regex=[^wrapping .*malloc
malloc called from:
.*
Hello world!
$
] 1.86 sec
```

Start by rerunning the linked GitHub Actions job and examining the code_api|sample.callstack test output on Ubuntu 22 x86-32. Compare the intermittent crash trace with the expected regular expression and the “Hello world!” completion. Done means the test reliably passes in that CI configuration.

Written by the indexing model from the issue text.