RFR: 8333641: Serial: Remove Generation::supports_tlab_allocation [v3]

[Albert Mingkun Yang]

> Trivial removing useless generation-level API. It was probably useful when there are a list of generations which have diff support for tlab. Now that we have only two generations, this API can be inlined/hardcoded to simplify the flow.

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 one commit:

  s1-remove-tlab

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Changes: https://git.openjdk.org/jdk/pull/19554/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19554&range=02
  Stats: 11 lines in 4 files changed: 0 ins; 9 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/19554.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19554/head:pull/19554

PR: https://git.openjdk.org/jdk/pull/19554