RFR: 8349351 : Combine Screen Inset Tests into a Single File

[anass baya]

While working on [JDK-6899304](https://bugs.openjdk.org/browse/JDK-6899304), we discovered that there are two tests meant to perform the same task.

The first test is located at test/jdk/java/awt/Multiscreen/MultiScreenInsetsTest/MultiScreenInsetsTest.java and was originally designed for multi-screen configurations on Linux platforms.

The second test, located at test/jdk/java/awt/Toolkit/ScreenInsetsTest/ScreenInsetsTest.java, is intended for single-screen configurations but lacks accuracy due to some workarounds to support Windows.

Now, the test at test/jdk/java/awt/Multiscreen/MultiScreenInsetsTest/MultiScreenInsetsTest.java has been updated to work across all platforms, including Windows, which was previously failing. As a result, it has been agreed to rename this test to ScreenInsetsTest, remove the condition that restricted its execution to multi-screen configurations, and remove the redundant test at test/jdk/java/awt/Toolkit/ScreenInsetsTest/ScreenInsetsTest.java.

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Commit messages:
 - Conbine Screen Insets Tests
 - Combine Screen Insets Tests

Changes: https://git.openjdk.org/jdk/pull/23449/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23449&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8349351
  Stats: 205 lines in 2 files changed: 16 ins; 145 del; 44 mod
  Patch: https://git.openjdk.org/jdk/pull/23449.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23449/head:pull/23449

PR: https://git.openjdk.org/jdk/pull/23449