[It] podman system prune --build clean up after terminated build: test flaky

[Honny1]

I observed this multiple times:

# podman-remote [options] system prune --build -f
           Error: unmarshalling into &types.SystemPruneReport{PodPruneReport:[]*types.PodPruneReport(nil), ContainerPruneReports:[]*reports.PruneReport{(*reports.PruneReport)(0xc0004ce0c0), (*reports.PruneReport)(0xc0004ce0f0), (*reports.PruneReport)(0xc0004ce120)}, ImagePruneReports:[]*reports.PruneReport(nil), NetworkPruneReports:[]*types.NetworkPruneReport(nil), VolumePruneReports:[]*reports.PruneReport(nil), ReclaimedSpace:0x3c61}, data "{\"PodPruneReport\":null,\"ContainerPruneReports\":[{\"Id\":\"aec04392e9b2fe7c4a36bc0cfa206dee35d7e403f7189df658ce909ccd598db7\",\"Size\":8219},{\"Id\":\"3d8a8789524a0c44a61baa49ceedda7be069b0b3d01255b24013d2fb82168c7e\",\"Err\":\"replacing mount point \\\"/tmp/CI_7Qsy/podman-e2e-213135586/subtest-1767990215/p/root/overlay/d9f554276b923c07bf708858b5f35774f9d2924fa4094b1583e56b33ae357af1/merged\\\": directory not empty\",\"Size\":7238},{\"Id\":\"e9ef46f3a3cd43c929b19a01013be4d052bcb228333e61dcb8eb7dd270ae44c2\",\"Size\":0}],\"ImagePruneReports\":null,\"NetworkPruneReports\":null,\"VolumePruneReports\":null,\"ReclaimedSpace\":15457}\n": json: cannot unmarshal string into Go struct field PruneReport.ContainerPruneReports.Err of type error

           [FAILED] Command failed with exit status 125. See above for error message.
           In [It] at: /var/tmp/go/src/github.com[/containers/podman/test/e2e/prune_test.go:633](https://github.com/containers/podman/blob/863f50ac23367c25e5f6b6edd9f4bc0a19eeb035/test/e2e/prune_test.go#L633) @ 10/10/25 05:21:47.69
         
           Full Stack Trace
             github.com/containers/podman/v5/test/e2e.init.func72.18()
             	/var/tmp/go/src/github.com[/containers/podman/test/e2e/prune_test.go:633](https://github.com/containers/podman/blob/863f50ac23367c25e5f6b6edd9f4bc0a19eeb035/test/e2e/prune_test.go#L633) +0x8f3
           ← Exit  [It] podman system prune --build clean up after terminated build - /var/tmp/go/src/github.com[/containers/podman/test/e2e/prune_test.go:591](https://github.com/containers/podman/blob/863f50ac23367c25e5f6b6edd9f4bc0a19eeb035/test/e2e/prune_test.go#L591) @ 10/10/25 05:21:47.69 (3.591s)

Full log: https://api.cirrus-ci.com/v1/artifact/task/6122990678573056/html/int-remote-fedora-42-root-host-sqlite.log.html#t--Podman-prune-podman-system-prune-build-clean-up-after-terminated-build--1