[jdk21u] RFR: 8313676: Amend TestLoadIndexedMismatch test to target intrinsic directly

[Aleksey Shipilev]

Clean backport to improve the test.

Additional testing:
 - [x] macosx-aarch64-server-fastdebug, the affected test is still sensitive to original fix

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Commit messages:
 - Backport 4b192a8dc37297f0746c0c68322e0168d9f47771

Changes: https://git.openjdk.org/jdk21u/pull/49/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=49&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8313676
  Stats: 7 lines in 2 files changed: 5 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk21u/pull/49.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/49/head:pull/49

PR: https://git.openjdk.org/jdk21u/pull/49