RFR: 8307078: Opensource and clean up five more AWT Focus related tests

[Alexander Zuev]

Cleaned up and ready to opensource:
java/awt/Focus/FocusForRemovedComponentTest
java/awt/Focus/FocusTraversalPolicyIAE
java/awt/Focus/InitialFocusTest
java/awt/Focus/LabelScrollbar
java/awt/Focus/ModalDialogInFocusEventTest

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Commit messages:
 - 8307078: Opensource and clean up five more AWT Focus related tests

Changes: https://git.openjdk.org/jdk/pull/13710/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13710&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307078
  Stats: 965 lines in 5 files changed: 965 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13710.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13710/head:pull/13710

PR: https://git.openjdk.org/jdk/pull/13710