[jdk21u-dev] RFR: 8325529: Remove unused imports from `ModuleGenerator` test file

[Goetz Lindenmaier]

I backport this for parity with 21.0.7-oracle

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Commit messages:
 - Backport d70156d2e2eddc311af12bc016b1ebb70efd92dd

Changes: https://git.openjdk.org/jdk21u-dev/pull/1306/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1306&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8325529
  Stats: 110 lines in 6 files changed: 56 ins; 40 del; 14 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1306.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1306/head:pull/1306

PR: https://git.openjdk.org/jdk21u-dev/pull/1306