[crac] RFR: 8371250: [CRaC] Remove old pid file in ImageScoreTest

[Radim Vansa]

The test is executed twice (with `-XX:[+-]UsePerfData`), and when the pauseengine pidfile is not removed this could lead to races.

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Commit messages:
 - 8371250: [CRaC] Remove old pid file in ImageScoreTest

Changes: https://git.openjdk.org/crac/pull/273/files
  Webrev: https://webrevs.openjdk.org/?repo=crac&pr=273&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8371250
  Stats: 6 lines in 1 file changed: 6 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/crac/pull/273.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/273/head:pull/273

PR: https://git.openjdk.org/crac/pull/273