RFR: 8307299: Move more DnD tests to open [v3]

[Alisen Chung]

> Added DnD tests

Alisen Chung has updated the pull request incrementally with one additional commit since the last revision:

  moved some function calls on EDT

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13759/files
  - new: https://git.openjdk.org/jdk/pull/13759/files/85714681..09ceaf0a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13759&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13759&range=01-02

  Stats: 8 lines in 1 file changed: 3 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/13759.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13759/head:pull/13759

PR: https://git.openjdk.org/jdk/pull/13759