docker-amd64-ubuntu-memcheck verify job is failing

[paleolimbot]

2026-05-17T01:14:38.7236710Z         Start 621: NanoarrowIpcTest/TestEndianFileFixture.NanoarrowIpcTestFileNativeEndian/generated_nested_dictionary.stream
2026-05-17T01:14:38.7388286Z 621/757 Test #621: NanoarrowIpcTest/TestEndianFileFixture.NanoarrowIpcTestFileNativeEndian/generated_nested_dictionary.stream
...
Uninitialized Memory Conditional - 621

https://github.com/apache/arrow-nanoarrow/actions/runs/25977719079/job/76360769759#step:4:4860

This can be run locally with NANOARROW_PLATFORM=ubuntu docker compose run --rm -e TEST_WITH_MEMCHECK=1 -e TEST_C_BUNDLED=0 verify (or something close)

[paleolimbot]

Closed by #891.