RFR: 8317119: Unused imports in the java.util.stream package

[Mourad Abbay]

Remove unused imports in the java.util.stream package.

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Commit messages:
 - Remove unused imports.

Changes: https://git.openjdk.org/jdk/pull/15949/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15949&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8317119
  Stats: 9 lines in 3 files changed: 0 ins; 9 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/15949.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15949/head:pull/15949

PR: https://git.openjdk.org/jdk/pull/15949