RFR: 8223543: [TESTBUG] Regression test java/awt/Graphics2D/DrawString/LCDTextSrcEa.java has issues

[Phil Race]

This test had problem described in the bug report, and most of it was related to being headful.
But actually the test didn't need to be headful - it did the actual rendering it wanted to test to
a software BufferedImage. So make it headless.
Also only Windows always supports LCD text, so run the test there and not Linux or Mac.

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Commit messages:
 - 8223543

Changes: https://git.openjdk.java.net/jdk/pull/8227/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8227&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8223543
  Stats: 51 lines in 1 file changed: 18 ins; 25 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8227.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8227/head:pull/8227

PR: https://git.openjdk.java.net/jdk/pull/8227