RFR: 8294842: Pass actual pending cards to G1Policy::update_young_length_bounds during young gen revise

[Thomas Schatzl]

Hi all,

  can I have reviews for this change that passes the actual amount of pending cards to `G1Policy::update_young_length_bounds` instead of some prediction during young gen revising?
That improves predictions quite a bit.

Depends on PR#10647, so please review that one first.

Testing: gha, local testing, tier1-5 with other changes in this patch series, perf testing with other changes in this patch series

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Depends on: https://git.openjdk.org/jdk/pull/10647

Commit messages:
 - initial version

Changes: https://git.openjdk.org/jdk/pull/10649/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10649&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294842
  Stats: 18 lines in 2 files changed: 7 ins; 1 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/10649.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10649/head:pull/10649

PR: https://git.openjdk.org/jdk/pull/10649