RFR: 8234532: Remove ThreadLocalAllocBuffer::_fast_refill_waste since it is never set [v2]

[Albert Mingkun Yang]

> It has some cascading effect; two performance variables, `fastWaste` and `maxFastWaste`, can be removed also.

Albert Mingkun Yang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:

 - merge
 - refill

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Changes: https://git.openjdk.java.net/jdk/pull/3756/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3756&range=01
  Stats: 42 lines in 5 files changed: 0 ins; 35 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3756.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3756/head:pull/3756

PR: https://git.openjdk.java.net/jdk/pull/3756