THRIFT-5000: Fixed path to the entrypoint to be relative to the Dockerfile

[kpumuk]

Fixing a failing build https://github.com/docker-library/official-images/actions/runs/26413710787/job/77753512175?pr=21530

• Did you create an Apache Jira ticket? THRIFT-5000
• If a ticket exists: Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"?
• Did you squash your changes to a single commit? (not required, but preferred)
• Did you do your best to avoid breaking changes? If one was needed, did you label the Jira ticket with "Breaking-Change"?
• If your change does not involve any code, include [skip ci] anywhere in the commit message to free up build resources.