Automation: Jenkins fix when handling complex variable values with corral

[izaac]

Summary

Fixes rancher/qa-tasks#1867

Occurred changes and/or fixed issues

The clean_corral() function was making the base64 kubeconfig invalid after striping characters. The intention was to clean the logs not the variable values.

Areas or cases that should be tested

Jenkins CI

Areas which could experience regressions

Jenkins CI

Checklist

• The PR is linked to an issue and the linked issue has a Milestone, or no issue is needed
• The PR has a Milestone
• The PR template has been filled out
• The PR has been self reviewed
• The PR has a reviewer assigned
• The PR has automated tests or clear instructions for manual tests and the linked issue has appropriate QA labels, or tests are not needed
• The PR has reviewed with UX and tested in light and dark mode, or there are no UX changes
• The PR has been reviewed in terms of Accessibility
• The PR has considered, and if applicable tested with, the three Global Roles Admin, Standard User and User Base