NIFI-13521 Remove nifi-headless-server-nar

[exceptionfactory]

Summary

NIFI-13521 Removes the nifi-headless-server-nar module and the optional headless profile from the build. The headless server classes remain available to support the current implementation of MiNiFi Java.

Tracking

Please complete the following tracking steps prior to pull request creation.

Issue Tracking

• [X] Apache NiFi Jira issue created

Pull Request Tracking

• [X] Pull Request title starts with Apache NiFi Jira issue number, such as NIFI-00000
• [X] Pull Request commit message starts with Apache NiFi Jira issue number, as such NIFI-00000

Pull Request Formatting

• [X] Pull Request based on current revision of the main branch
• [X] Pull Request refers to a feature branch with one commit containing changes

Verification

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Build

• [ ] Build completed using mvn clean install -P contrib-check
  • [ ] JDK 21

Licensing

• [ ] New dependencies are compatible with the Apache License 2.0 according to the License Policy
• [ ] New dependencies are documented in applicable LICENSE and NOTICE files

Documentation

• [ ] Documentation formatting appears as expected in rendered files