[crac] RFR: 8357977: [CRaC] Unused imports in CRaC's classes

[Timofei Pushkin]

Removes unused imports from CRaC's Java code.

-------------

Commit messages:
 - Remove unused imports

Changes: https://git.openjdk.org/crac/pull/232/files
  Webrev: https://webrevs.openjdk.org/?repo=crac&pr=232&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8357977
  Stats: 8 lines in 4 files changed: 0 ins; 8 del; 0 mod
  Patch: https://git.openjdk.org/crac/pull/232.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/232/head:pull/232

PR: https://git.openjdk.org/crac/pull/232