RFR: 8282727: Parallel: Remove PSPromotionManager::_totally_drain

[Albert Mingkun Yang]

Simple change of removing a redundant boolean field.

Test: hotspot_gc

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Commit messages:
 - pgc-flush

Changes: https://git.openjdk.java.net/jdk/pull/7725/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7725&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282727
  Stats: 4 lines in 2 files changed: 0 ins; 2 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7725.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7725/head:pull/7725

PR: https://git.openjdk.java.net/jdk/pull/7725