fix: revert api client for UNENROLL_DONE signal

[muhammad-ammar]

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[muneebGH]

LGTM

[edx-pipeline-bot]

EdX Release Notice: This PR has been deployed to the staging environment in preparation for a release to production.

[edx-pipeline-bot]

EdX Release Notice: This PR has been deployed to the production environment.

[edx-pipeline-bot]

EdX Release Notice: This PR has been deployed to the production environment.