[jdk11u-dev] RFR: 8208699: remove unneeded imports from runtime tests

[Amos Shi]

Backport of [JDK-8208699](https://bugs.openjdk.org/browse/JDK-8208699)

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Commit messages:
 - Backport 940ac1cddc3317ced9a5c9b6b0f1c85b8fd6cdaf

Changes: https://git.openjdk.org/jdk11u-dev/pull/2303/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2303&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8208699
  Stats: 2 lines in 2 files changed: 0 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2303.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2303/head:pull/2303

PR: https://git.openjdk.org/jdk11u-dev/pull/2303