[lworld] RFR: 8370217: [lworld] Crash in add_migrated_value_classes after merging JDK-8350550 [v2]

[Matias Saavedra Silva]

> The method add_migrated_value_classes() is being called in non-preview mode leading to an assert due to the expected classes not being present in the AOT cache. The check for `EnableValhalla` is replaced with a check for preview mode. Verified with tier 1-5 tests.

Matias Saavedra Silva has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Coleen comments
 - Merge branch 'lworld' into crash_8370217
 - 8370217: [lworld] Crash in add_migrated_value_classes after merging JDK-8350550

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Changes:
  - all: https://git.openjdk.org/valhalla/pull/1698/files
  - new: https://git.openjdk.org/valhalla/pull/1698/files/8c9e3017..3546f6d8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1698&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1698&range=00-01

  Stats: 12484 lines in 451 files changed: 6693 ins; 3205 del; 2586 mod
  Patch: https://git.openjdk.org/valhalla/pull/1698.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1698/head:pull/1698

PR: https://git.openjdk.org/valhalla/pull/1698