[lworld] Integrated: 8250823: [lworld] Various cleanups and small fixes in JIT code

[Tobias Hartmann]

- Rename is_never_null -> is_null_free in C1 code
- Use is_invalid_super() in ciInstanceKlass::can_be_inline_klass() and clean up code
- Handle OOM when creating ciFlatArrayKlass
- Removed some dead code from inlinetypenode.cpp and did various refactorings
- Make sure non-captured initializing stores are removed when removing the corresponding allocation
- Added @key randomness to tests

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Commit messages:
 - 8250823: [lworld] Various cleanups and small fixes in JIT code

Changes: https://git.openjdk.java.net/valhalla/pull/125/files
 Webrev: https://webrevs.openjdk.java.net/valhalla/125/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8250823
  Stats: 195 lines in 35 files changed: 60 ins; 58 del; 77 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/125.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/125/head:pull/125

PR: https://git.openjdk.java.net/valhalla/pull/125