NIFI-15126 Enable parallel execution in GitHub ci-workflow

[exceptionfactory]

Summary

NIFI-15126 Enables parallel execution for Maven Compile and Verify steps in the GitHub ci-workflow using one thread per available processor reported.

Recent Maven updates and GitHub runner upgrades provide a better foundation for enabling this feature in GitHub workflows. Other system and integration test workflows are not good candidates for parallel execution at this time due to use of common network ports among other potential resource considerations.

Tracking

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

Issue Tracking

• Apache NiFi Jira issue created

Pull Request Tracking

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

Pull Request Formatting

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

Verification

Please indicate the verification steps performed prior to pull request creation.

Build

• Build completed using ./mvnw clean install -P contrib-check
  • JDK 21
  • JDK 25

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