[ci] License checks leave directory streams open on traversal failure

[taoran92]

Purpose

Fixes #10445.

CI license checks can leave directory resources open when traversal or filtering fails in JarFileChecker.getBuildJars() or NoticeFileChecker.findNoticeFiles(). Wrap both Files.walk() streams in try-with-resources to ensure cleanup on success and failure.

Tests

• mvn -o -pl tools/ci/paimon-ci-tools -DwildcardSuites=none -Dtest=JarFileCheckerTest,NoticeFileCheckerTest test passed: 27 tests, including Checkstyle and Spotless checks.
• git diff --check passed.
• No new tests were added for this resource-lifetime change.

[JingsongLi]

Closing under the requested production/end-to-end contribution triage.

I traced both walkers to LicenseChecker.main and the current artifact-licensing workflow. The checker runs once in an isolated mvn exec:java ... -N step; a traversal/filtering exception aborts that step. The proposed try-with-resources change does not change a licensing result, recover the failed check, or address a demonstrated long-lived/repeated caller. Successful exhaustive Files.walk traversal already closes its directory iterators. The linked #10138 concerns Files.list during sink configuration loading, where resources can remain open after successful loading; that is a different lifecycle.

The implementation is straightforward and the 27 JarFileCheckerTest / NoticeFileCheckerTest tests passed on JDK 8 with standard Maven validation. For this standalone CI failure path, the current evidence supports resource-cleanup hygiene but does not establish an end-to-end production or CI reliability outcome that warrants a separate contribution. A real repeated invocation, recovery path, or failing licensing workload caused by retained directory resources would justify reopening with targeted evidence.

Reviewed head: 800b0a2e8bf50e752cecedfd29958dbf5111e677.