Remove ppc64le and s390x release unittest

[khrm]

Arch-specific unit tests can't be run. We have only one arch available during release.

Changes

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you review them:

• Has Docs included if any changes are user facing
• Has Tests included if any functionality added or changed
• Tested your changes locally (if this is a code change)
• Follows the commit message standard
• Meets the Tekton contributor standards (including functionality, content, code)
• Has a kind label. You can add a comment on this PR that contains /kind <type>. Valid types are bug, cleanup, design, documentation, feature, flake, misc, question, tep
• Release notes block below has been updated with any user-facing changes (API changes, bug fixes, changes requiring upgrade notices or deprecation warnings)
• Release notes contain the string "action required" if the change requires additional action from users switching to the new release

Release Notes

NONE

[khrm]

/kind misc

[alan-ghelardi]

/approve

[khrm]

Without this, we get exec error during the release.

[adambkaplan]

/lgtm

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: adambkaplan, alan-ghelardi

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

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [adambkaplan,alan-ghelardi]

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

[enarha]

/lgtm