[jdk11u-dev] RFR: 8267860: Off-by-one bug when searching arrays in AlpnGreaseTest

[Amos]

- This is the back port of [JDK-8267860](https://bugs.openjdk.org/browse/JDK-8267860)
- The original commit is https://github.com/openjdk/jdk/commit/2adef6a1f84d478bb38b179795f08ffa43680e36
- The test case has been verified working in local

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Commit messages:
 - Backport 2adef6a1f84d478bb38b179795f08ffa43680e36

Changes: https://git.openjdk.org/jdk11u-dev/pull/2144/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2144&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8267860
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2144.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2144/head:pull/2144

PR: https://git.openjdk.org/jdk11u-dev/pull/2144