Fix image filter in list images API

[TP-O]

JSON filter input

{
    "label": [
        "org.opencontainers.image.ref.name=ubuntu", 
        "org.opencontainers.image.version=22.04"
    ]
}

ImageListOptions.Filter is generated

["label=org.opencontainers.image.ref.name=ubuntu=org.opencontainers.image.version=22.04"]

After fix

["label=org.opencontainers.image.ref.name=ubuntu", "label=org.opencontainers.image.version=22.04]

Close #18092

Does this PR introduce a user-facing change?

None

[openshift-ci]

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