RFR: 8255487: Mark SandboxAppTest unstable on Windows

Tue Oct 27 23:16:22 UTC 2020

This test is somewhat unstable on Windows. Even after the test timeout was increased to 25 seconds, it still times out on some Windows machines.

The proposed fix is to mark this test unstable on Windows so our nightly build will not execute it and get frequent failures. It can still be run by passing `-PUNSTABLE_TEST=true` to gradle. For example:

gradle --info -PUNSTABLE_TEST=true -PFULL_TEST=true cleanTest :systemTests:test --tests SandboxAppTest

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Commit messages:
 - 8255487: Mark SandboxAppTest unstable on Windows

Changes: https://git.openjdk.java.net/jfx/pull/340/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=340&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255487
  Stats: 8 lines in 1 file changed: 8 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/340.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/340/head:pull/340

PR: https://git.openjdk.java.net/jfx/pull/340