RFR: 8370112: Remove VM_Version::supports_fast_class_init_checks() in platform-specific code

[David Holmes]

Please review this simple enhancement to remove runtime checks for `VM_Version::supports_fast_class_init_checks()` in platform specific code, and replace them with asserts - as we know statically whether a given platform supports it.

The changes are the same for each platform.

Testing
 - building all platforms via GHA
 - tiers 1-3 (sanity)

Thanks

-------------

Commit messages:
 - Fixed overzealous code removal
 - 8370112: Remove VM_Version::supports_fast_class_init_checks() in platform-specific code

Changes: https://git.openjdk.org/jdk/pull/29293/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29293&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370112
  Stats: 112 lines in 10 files changed: 10 ins; 6 del; 96 mod
  Patch: https://git.openjdk.org/jdk/pull/29293.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29293/head:pull/29293

PR: https://git.openjdk.org/jdk/pull/29293