RFR: 8369097: Parallel: Support allocation in from space when heap is too full [v2]

[Albert Mingkun Yang]

> Support allocation in from-space of young-gen in extreme cases (heap is almost full), so that gc-log shows used-heap is almost at max-heap when OOM is thrown.
> 
> Test: tier1-5

Albert Mingkun Yang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into pgc-allocate-in-from-space
 - pgc-allocate-in-from-space

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/27620/files
  - new: https://git.openjdk.org/jdk/pull/27620/files/7c1efc07..403e34fc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27620&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27620&range=00-01

  Stats: 6422 lines in 168 files changed: 5007 ins; 878 del; 537 mod
  Patch: https://git.openjdk.org/jdk/pull/27620.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27620/head:pull/27620

PR: https://git.openjdk.org/jdk/pull/27620