[jfx-tests] RFR: 8316116: Ignore a single failing test case from Effects2Test

[Ajit Ghaisas]

test/scenegraph/functional/graphics/Effects2Test.java has a total of 123 test cases. Out of which 122 test cases pass and 1 test case (Lightningspotlight) fails consistently. Right now, the root cause of this test failure is unknown.

This PR marks this test case with `@Ignore`. It will be fixed in future under [JDK-8316117](https://bugs.openjdk.org/browse/JDK-8316117).

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Commit messages:
 - ignore single test case

Changes: https://git.openjdk.org/jfx-tests/pull/10/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx-tests&pr=10&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316116
  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jfx-tests/pull/10.diff
  Fetch: git fetch https://git.openjdk.org/jfx-tests.git pull/10/head:pull/10

PR: https://git.openjdk.org/jfx-tests/pull/10