[ruby/rubygems] Use IO.copy_stream to drain remaining gzip data instead of read

Replace gzio.read with IO.copy_stream(gzio, IO::NULL) to avoid
allocating a potentially large string when discarding unconsumed
compressed data.

ruby/rubygems@e4d0196887

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 2 people

lib/rubygems/package.rb

@@ -561,7 +561,7 @@ def open_tar_gz(io) # :nodoc:
       # "attempt to close unfinished zstream; reset forced" warning
       # when the GzipReader is closed with unconsumed compressed data.
       begin
-        gzio.read
+        IO.copy_stream(gzio, IO::NULL)
       rescue Zlib::GzipFile::Error, IOError
         nil
       end