Integrated: 8282089: [BACKOUT] Parallel: Refactor PSCardTable::scavenge_contents_parallel

[Albert Mingkun Yang]

Revert a commit to reduce tier1 noise while investigation.

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Commit messages:
 - Revert "8280783: Parallel: Refactor PSCardTable::scavenge_contents_parallel"

Changes: https://git.openjdk.java.net/jdk/pull/7529/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7529&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282089
  Stats: 277 lines in 2 files changed: 102 ins; 103 del; 72 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7529.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7529/head:pull/7529

PR: https://git.openjdk.java.net/jdk/pull/7529