RFR: 8349688: Crash assert(!_g1h->heap_region_containing(p)->is_survivor()) failed: Should have filtered out from-newly allocated survivor references already

[Ivan Walulya]

Hi,

Please review this fix to the bug in setting a region index to the optional cset. The crash happens because the incorrect `_index_in_opt_cset` refers to a region that has already been evacuated.

Testing: tier5-common-apps

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Commit messages:
 - set_index_in_opt_cset correctly

Changes: https://git.openjdk.org/jdk/pull/23568/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23568&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8349688
  Stats: 6 lines in 1 file changed: 4 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/23568.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23568/head:pull/23568

PR: https://git.openjdk.org/jdk/pull/23568