fix image build not using cache

[fulminemizzega]

This commit fixes issue #528 by adding a default value to parameters layers and outputformat. This change aligns the behavior with podman-remote.

@inknos take a look, I've also added a test for this PR

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: fulminemizzega Once this PR has been reviewed and has the lgtm label, please assign mheon for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment Approvers can cancel approval by writing /approve cancel in a comment

[inknos]

/packit retest-failed

[Honny1]

/packit retest-failed

[inknos]

/packit build