[crac] RFR: 8365143: [CRaC] CRaCIgnoreRestoreIfUnavailable tests do not check exit value

[Timofei Pushkin]

Adds missing exit value checks.

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Commit messages:
 - Add missing waitForSuccess

Changes: https://git.openjdk.org/crac/pull/260/files
  Webrev: https://webrevs.openjdk.org/?repo=crac&pr=260&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8365143
  Stats: 9 lines in 4 files changed: 4 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/crac/pull/260.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/260/head:pull/260

PR: https://git.openjdk.org/crac/pull/260