<Swing Dev> RFR: 8258233: Reenable another fixed problemlisted test

[Prasanta Sadhukhan]

javax/swing/JFileChooser/6868611/bug6868611.java was failing in windows in mach5 testing but was fixed in JDK-8198004 later on, but this test was not removed from problemList. We can remove it from problemlist now.
Tested for several iteration in mach5. Link in JBS.

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Commit messages:
 - 8258233: Reenable another fixed problemlisted test

Changes: https://git.openjdk.java.net/jdk/pull/1766/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1766&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258233
  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1766.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1766/head:pull/1766

PR: https://git.openjdk.java.net/jdk/pull/1766