RFR: 8281585: Remove unused imports under test/lib and jtreg/gc [v2]

[Leo Korinth]

> Remove unused imports under test/lib and jtreg/gc. They create lots of warnings if editing using an IDE. Tests in hotspot_gc passed.

Leo Korinth has updated the pull request incrementally with one additional commit since the last revision:

  updating copyright

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7426/files
  - new: https://git.openjdk.java.net/jdk/pull/7426/files/6aaa1a3a..7d3e7a1b

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7426&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7426&range=00-01

  Stats: 59 lines in 59 files changed: 0 ins; 0 del; 59 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7426.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7426/head:pull/7426

PR: https://git.openjdk.java.net/jdk/pull/7426