RFR: 8291000: C2: Purge LoadPLocked and Store*Conditional nodes

Tue Jul 26 19:00:26 UTC 2022

The last uses for these nodes was the inline contiguous allocations. With [JDK-8290706](https://bugs.openjdk.org/browse/JDK-8290706), these nodes are not used anymore and can be cleaned up.

Testing:
 - [x] Linux x86_64 fastdebug tier1
 - [ ] Linux x86_32 fastdebug tier1
 - [ ] Linux AArch64 fastdebug tier1
 - [x] Linux x86_64 Zero build
 - [x] Linux AArch64 cross-build
 - [x] Linux ARM cross-build
 - [x] Linux S390X cross-build
 - [x] Linux PPC64 cross-build
 - [x] Linux RISC-V cross-build

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/9636/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9636&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291000
  Stats: 556 lines in 17 files changed: 0 ins; 552 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/9636.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9636/head:pull/9636

PR: https://git.openjdk.org/jdk/pull/9636