RFR: 8277824: Remove empty RefProcSubPhasesWorkerTimeTracker destructor [v2]

[Albert Mingkun Yang]

> Simple change removing effectively dead code, and some general cleanup.
> 
> Test: hotspot_gc

Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:

  review

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6555/files
  - new: https://git.openjdk.java.net/jdk/pull/6555/files/38c66d66..ae0bcf93

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6555&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6555&range=00-01

  Stats: 3 lines in 2 files changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6555.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6555/head:pull/6555

PR: https://git.openjdk.java.net/jdk/pull/6555