Yarn: add integration test for missing lockfile

[ejegrova]

Adding test for a yarn project which is missing a lockfile. This results in failure in cachi2.

STONEBLD-2075

Maintainers will complete the following section

• Commit messages are descriptive enough
• Code coverage from testing does not decrease and new code is covered
• N/A Docs updated (if applicable)
• N/A Docs links in the code are still valid (if docs were updated)

Note: if the contribution is external (not from an organization member), the CI
pipeline will not run automatically. After verifying that the CI is safe to run:

• approve GitHub Actions workflows by clicking a button
• approve the Red Hat Trusted App Pipeline container build by commenting /ok-to-test
  (as is the standard for Pipelines as Code)

[ejegrova]

testing repo: https://github.com/cachito-testing/cachi2-yarn-berry/tree/missing_lockfile

[taylormadore]

LGTM 👍