Leaky stream handling in test utilities (TestFileUtils, TestFileProcessor)

[elharo]

Affected version: HEAD

Files:

• maven-resolver-test-util/src/main/java/org/eclipse/aether/internal/test/util/TestFileUtils.java:172-325
• maven-resolver-test-util/src/main/java/org/eclipse/aether/internal/test/util/TestFileProcessor.java:63-151

Methods manually close streams in try-catch-finally blocks instead of using try-with-resources. If an explicit close() call throws before the finally block, open resources are leaked. Functionally correct in happy-path but fragile.

Originally reported in #1944.