RFR: 8303920: Avoid calling out to python in DataDescriptorSignatureMissing test [v7]

[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:

  The END header LOC offset field and the second entry's CEN LOC offset fields need to be update to account for the four missing signature bytes.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12959/files
  - new: https://git.openjdk.org/jdk/pull/12959/files/0fb30670..5dd9891b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12959&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12959&range=05-06

  Stats: 23 lines in 1 file changed: 22 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12959.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/12959/head:pull/12959

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