RFR: 8330972: Serial: Inline Generation::max_contiguous_available

[Guoxiong Li]

Hi all,

This patch removes the method `Generation::max_contiguous_available` and uses `contiguous_available` instead in `TenuredGeneration::promotion_attempt_is_safe` (because it is in old-gen).

Thanks for taking the time to review.

Best Regards,
-- Guoxiong

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Commit messages:
 - JDK-8330972

Changes: https://git.openjdk.org/jdk/pull/18929/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18929&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8330972
  Stats: 14 lines in 3 files changed: 0 ins; 12 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/18929.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18929/head:pull/18929

PR: https://git.openjdk.org/jdk/pull/18929