Make ZipFileTest#testHugeZipFile faster, and reduce ZipFile memory usage.

This test was timing out because of unbuffered I/O.

ZipFile was creating an unnecessary byte[] when writing out the central
directory. In the case of these tests, that was an extra 3MiB of heap!

Bug: 6481730
Change-Id: I75acac35c556ad5fdc8b06bc616c11244d6b6c55
2 files changed