Exclude macOS metadata from release archives

[wu-sheng]

Fix macOS metadata in release archives

The 9.7.0 binary archive contains AppleDouble ._* entries generated by macOS tar from extended file attributes. The ._*.jar sidecars are then scanned as plugin JARs and produce loading errors.

Set COPYFILE_DISABLE=1 and exclude existing ._* and .DS_Store files directly in the source and binary tar commands. Update the release guide and changelog.

Validation: exercised the exact updated commands with fixture files on macOS BSD tar and Linux GNU tar 1.35 (Debian). Both archives contained zero metadata entries and preserved plugin contents; source packaging still excluded .git. On macOS, exclusions alone still generated five metadata entries. Shell syntax and git diff --check passed.

• Add a unit test to verify that the fix works. Packaging commands were tested directly with temporary fixtures; no Java code changed.
• Explain briefly why the bug exists and how to fix it.
• Closes [Bug] Java Agent 9.7.0 release tarball contains macOS AppleDouble ._ files skywalking#14080.
• Update the CHANGES log.