fix(WCOW): fix file access failure for multistage builds #4955

Job	Run time
govulncheck	1m 2s
prepare	4s
binaries (darwin/amd64)	1m 6s
binaries (darwin/arm64)	58s
binaries (linux/amd64)	1m 53s
binaries (linux/arm/v7)	1m 49s
binaries (linux/arm64)	2m 5s
binaries (linux/s390x)	1m 57s
binaries (linux/ppc64le)	2m 3s
binaries (linux/riscv64)	1m 55s
binaries (windows/amd64)	1m 38s
binaries (windows/arm64)	1m 35s
test / prepare	1m 47s
test / run (containerd, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	8m 1s
test / run (containerd-rootless, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integr...	9m 21s
test / run (containerd-1.6, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	7m 59s
test / run (containerd-snapshotter-stargz, ./client ./cmd/buildctl ./worker/containerd ./solver ./fronte...	12m 58s
test / run (oci, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	10m 44s
test / run (oci-rootless, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	7m 25s
test / run (oci-rootless-slirp4netns-detachnetns, ./client ./cmd/buildctl ./worker/containerd ./solver ....	5m 28s
test / run (oci-snapshotter-stargz, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, int...	7m 35s
test / run (./..., 1, integration gateway)	9m 51s
test / run (./client, containerd, nydus, integration)	8m 0s
test / run (./client, oci, nydus, integration)	7m 21s
test / run (./..., nydus, 1, integration)	4m 41s
image	9m 8s
image (rootless)	8m 40s
release	10s
scout	0s
	2h 17m 14s

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