[test] Move gzip helper from core production code to hive test

[cxzl25]

Purpose

CompressUtils.gzipCompressFile was only used by a single Hive IT test
(HiveCatalogFormatTableITCaseBase) but was placed in paimon-core main,
unnecessarily inflating the production jar.

• Delete CompressUtils from paimon-core/src/main/java
• Inline the logic as a private static helper in the test base class
• Fix the resource leak in the process: the original implementation
  only closed streams on the happy path; rewrite using try-with-resources
  so streams are always closed even when an IOException is thrown

Tests

GHA

[JingsongLi]

Making this helper local to the Hive test leaves another caller broken. paimon-spark/paimon-spark-ut/src/test/scala/org/apache/paimon/spark/sql/FormatTableTestBase.scala still imports org.apache.paimon.utils.CompressUtils and calls CompressUtils.gzipCompressFile, so deleting the core class will make the Spark test module fail to compile. Please either move the helper to a shared test utility used by both modules, or update the Spark test to use its own/local helper as well.