contrib/buildahimage: set config correctly for rootless build user

[flouthoc]

For image published at quay.io/containers/buildah buildah should correctly use fuseoverlay for rootless build user fuse-overlayfs.

Closes: #4669

[NO NEW TESTS NEEDED]

What type of PR is this?

/kind api-change
/kind bug
/kind cleanup
/kind deprecation
/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake
/kind other

What this PR does / why we need it:

How to verify it

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?

contrib/buildahimage: set config correctly for rootless `build` user

[rhatdan]

$ podman run --user build --device /dev/fuse -v /tmp/dan/:/tmp:Z quay.io/buildah/stable buildah build /tmp
time="2023-07-03T10:35:39Z" level=warning msg="Error loading container config when searching for local runtime: mkdir /home/build/rundir/libpod: no such file or directory"
time="2023-07-03T10:35:39Z" level=error msg="failed to setup From and Build flags: failed to get container config: mkdir /home/build/rundir/libpod: no such file or directory"

Does this fix this issue?

[rhatdan]

LGTM

[flouthoc]

@containers/buildah-maintainers PTAL

[rhatdan]

@TomSweeneyRedHat @giuseppe @nalind @vrothberg PTAL

[giuseppe]

LGTM

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: flouthoc, giuseppe

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[TomSweeneyRedHat]

LGTM

[TomSweeneyRedHat]

/lgtm

[TomSweeneyRedHat]

/hold
for happy tests

[TomSweeneyRedHat]

@flouthoc PTAL, tests are not at all happy

[flouthoc]

@TomSweeneyRedHat It was caused due to temporary outage of registry.k8s.io:

[flouthoc]

/hold cancel