Update system tests to handle zstd:chunked images

[mtrmac]

• Compare image configs, not IDs, when checking image identity from different way of pulling them
• Try to make the additional image store test a bit more robust
• Remove an image identity assumption from the “load by URL” test.

Working on test failures as discussed in containers/storage#2130 .

At this point absolutely untested, and I don’t really know what I’m doing.

Cc: @edsantiago — perhaps read this only later after this is at least minimally shown to be working.

Does this PR introduce a user-facing change?

None

[openshift-ci]

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[packit-as-a-service]

Ephemeral COPR build failed. @containers/packit-build please check.

[mtrmac]

Yeah, this is nowhere close to working, ignore for now.

---

Also [255] podman-kube@.service template with rollback

#|     FAIL: global auto-update policy gets applied
   #| expected: '.*podman-kube@-tmp-podman_bats.roXH3U-test.yaml.service,.* (test_pod-a),quay.io/libpod/testimage:20241010,false,registry.*' (using expr)
   #|   actual: 'podman-kube@-tmp-podman_bats.roXH3U-test.yaml.service,c104ff383fd7 (test_pod-a),quay.io/libpod/testimage:20241010,pending,registry'
   #|         > 'podman-kube@-tmp-podman_bats.roXH3U-test.yaml.service,aa204347c263 (test_pod-b),localhost/image:Kl8NYi3jxL,false,local'

[mtrmac]

@edsantiago With this, make localsystem is passing for me in #24287 , and it should continue to work with non-chunked images.

Could you take a preliminary look to make sure I’m not missing/breaking the point of these tests, please?

See individual commit messages for details.

[edsantiago]

@mtrmac I've been peeking periodically and have seen no major cause for alarm. I will not be able to give this a thorough review until Monday. Apologies.

[mtrmac]

@edsantiago Thanks! The peeks are reassuring already, and I need to make this pass first. There’s no rush at all.

[edsantiago]

I think the 120 tests need a complete revamp: my initial decision to use $IMAGE has backfired. Next week I will look into a different safer approach.

[mtrmac]

Ready for review:
System tests are passing both here, with current images, and in #24287 , with zstd:chunked images. (Integration tests are failing with zstd:chunked images, I’ll work on that in a separate PR.)