NIFI-16304 Retain connector verification and purge results for one minute

[markap14]

Summary

NIFI-16304

Submitting a connector configuration verification can remove another connector's completed verification result after only one millisecond, causing a subsequent poll to return HTTP 404. The asynchronous request manager expects a retention interval in milliseconds, but the verification and FlowFile purge managers pass 1L.

Set both retention intervals to one minute. Add a system regression that completes verification on one connector, submits verification on another connector, and confirms the first result remains retrievable.

Verification

• The regression failed with HTTP 404 before the fix and passed after the fix: 1 test, 0 failures, 0 errors, 0 skipped.

  mvn -pl nifi-system-tests/nifi-system-test-suite -Pintegration-tests,skip-unit-tests '-Dit.test=ConnectorCrudIT#testCompletedConfigVerificationRetainedWhenAnotherConnectorIsVerified' verify

• Clean-installed nifi-web-api, nifi-server-nar, and nifi-system-test-suite before running the system test. Confirmed the assembled runtime contains the rebuilt server NAR.
• mvn test in nifi-web-api: 642 tests passed.
• Checkstyle and PMD passed for both changed modules using the repository's configured versions. A temporary Maven Central mirror was used after the primary endpoint returned HTTP 429.
• Verification used JDK 21. The full ./mvnw clean install -P contrib-check and JDK 25 matrix were not run for this change.

No dependencies or documentation changed. The system regression covers verification-result retention; the identical purge-retention correction is not separately exercised by this test.