RFR: 8303920: Avoid calling out to python in DataDescriptorSignatureMissing test [v3]

[Eirik Bjorsnos]

> 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.

Eirik Bjorsnos has updated the pull request incrementally with one additional commit since the last revision:

  Use "Signatureless" consistently

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12959/files
  - new: https://git.openjdk.org/jdk/pull/12959/files/064aa3b9..a20faeea

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12959&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12959&range=01-02

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 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