NIFI-10075 Improve TestListSFTP configuration verification

[exceptionfactory]

Summary

NIFI-10075 Improves the behavior of TestListSFTP to reduce the possibility of intermittent failures. The assertVerificationSuccess() method previously ran before each test method, attempting to verify server connectivity multiple times. Changing the private method to a regular test method checks runs the check once, minimizing potential issues and allowing the startServer method to complete before running. Additional changes include upgrading the test to JUnit 5 and removing unnecessary exception declarations.

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 mvn clean install -P contrib-check
  • JDK 8
  • JDK 11
  • JDK 17

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