RFR: 8285878: [TestBug] LocalStorageTest and UserDataDirectoryTest don't always cleanup data dirs

[Jay Bhaskar]

Issue: "LocalStorageTest and UserDataDirectoryTest don't always cleanup data dirs"
Solution:
1. All data directories must only be created under the "build" dir. In addition to being a best practice, at least they will be cleaned up by "gradle clean"
2. There should be an @AfterClass method that deletes the data dirs
3. There should be an @BeforeClass method that also deletes the data dirs prior to running the tests in case it wasn't cleaned up previously

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Commit messages:
 - Fix: move dir creation in build dir ,so that it would be cleaned

Changes: https://git.openjdk.org/jfx/pull/1100/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1100&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8285878
  Stats: 25 lines in 2 files changed: 12 ins; 5 del; 8 mod
  Patch: https://git.openjdk.org/jfx/pull/1100.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1100/head:pull/1100

PR: https://git.openjdk.org/jfx/pull/1100