[CheckpointWrapper] Use correct extension during atomic writing

4 jobs for atomic-writing in 16 minutes and 16 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #240768
docker
build_linux_37

00:12:39

passed #240769
docker
build_linux_38

00:11:23

passed #240766
intel macos
build_macos_intel_37

00:16:16

passed #240767
intel macos
build_macos_intel_38

00:13:46