RFR: 8273144: Remove unused top level "Sample Collection Set Candidates" logging

[Thomas Schatzl]

Hi all,

  please review this trivial(?) removal of a log message and associated unused code.

This is a leftover from JDK-8017163 and the merge with the BatchedGangTask API (there is a "Sample CSet Candidates" log which is used in post evacuation phase 2).

Testing: changed TestGCLogMessages test case, compilation

Thanks,
  Thomas

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Commit messages:
 - Remove unused log entry

Changes: https://git.openjdk.java.net/jdk/pull/5304/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5304&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273144
  Stats: 10 lines in 3 files changed: 0 ins; 10 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5304.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5304/head:pull/5304

PR: https://git.openjdk.java.net/jdk/pull/5304