RFR: 8329771: G1: Refactor G1BlockOffsetTable::verify

[Guoxiong Li]

Hi all,

This patch verifies the BOT after writing the BOT and changes the method name for consistence, just like `SerialBlockOffsetTable::verify_for_block` and `ObjectStartArray::verify_for_block`.

The test `make test-tier1_gc` passed locally. Thanks for taking the time to review.

Best Regards,
-- Guoxiong

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Commit messages:
 - JDK-8329771

Changes: https://git.openjdk.org/jdk/pull/18711/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18711&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329771
  Stats: 57 lines in 3 files changed: 8 ins; 34 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/18711.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18711/head:pull/18711

PR: https://git.openjdk.org/jdk/pull/18711