[lworld] RFR: 8376122: [lworld] Cleanup of SA use of aconst_init and withfield

[Paul Hübner]

Hi all,

This PR removes leftover bytecode definitions in various places from older Valhalla models that we are no longer using in the virtual machine:
* `aconst_init`
* `withfield`

`Bytecodes.java` also had references to qworld codes that I cleaned up while I was in the area.
* `qgetfield`
* `qputfield`

The SA should now have bytecode-parity with mainline & the VM.

Testing: tiers 1-3.

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Commit messages:
 - Clean up unused bytecodes.

Changes: https://git.openjdk.org/valhalla/pull/1969/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1969&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8376122
  Stats: 56 lines in 7 files changed: 0 ins; 14 del; 42 mod
  Patch: https://git.openjdk.org/valhalla/pull/1969.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1969/head:pull/1969

PR: https://git.openjdk.org/valhalla/pull/1969