RFR: 8303920: Avoid calling out to python in DataDescriptorSignatureMissing test

[Eirik Bjorsnos]

The message from this sender included one or more files
which could not be scanned for virus detection; do not
open these files unless you are certain of the sender's intent.

----------------------------------------------------------------------
Please review this PR which brings  the DataDescriptorSignatureMissing test back to life.

This test currently calls out to Python to create a test vector ZIP with a Data Descriptor without the recommended but optional signature. The Python dependency has turned out to be very brittle, so the test is currently marked with `@ignore` 

The PR replaces Python callouts with directly creating the test vector ZIP in the test itself. We can then remove the `@ignore`tag and run this useful test automatically.

-------------

Commit messages:
 - Update copyright years
 - Add method comments
 - Instead of calling out to python, create a ZIP file and remove the data descriptor signature.

Changes: https://git.openjdk.org/jdk/pull/12959/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12959&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303920
  Stats: 123 lines in 1 file changed: 22 ins; 66 del; 35 mod
  Patch: https://git.openjdk.org/jdk/pull/12959.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12959/head:pull/12959

PR: https://git.openjdk.org/jdk/pull/12959