[jdk18] RFR: 8278824: Increase chunks per region for G1 vm root scan

[William Kemper]

Rebased onto 18. Original PR is here: https://github.com/openjdk/jdk/pull/6840

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Commit messages:
 - 8278824: Increase chunks per region for G1 vm root scan

Changes: https://git.openjdk.java.net/jdk18/pull/66/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18&pr=66&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278824
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk18/pull/66.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18 pull/66/head:pull/66

PR: https://git.openjdk.java.net/jdk18/pull/66