[llvm] RegAlloc: Fix verifier error after failed allocation (PR #119690)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-expensive-checks-debian` running on `gribozavr4` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/16/builds/14149

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/AMDGPU/schedule-amdgpu-tracker-physreg-crash.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 1: not /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -mattr=+xnack -amdgpu-use-amdgpu-trackers=1  2>&1  < /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/schedule-amdgpu-tracker-physreg-crash.ll | /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck -check-prefixes=ERR-GCNTRACKERS /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/schedule-amdgpu-tracker-physreg-crash.ll
+ not /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -mattr=+xnack -amdgpu-use-amdgpu-trackers=1
+ /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck -check-prefixes=ERR-GCNTRACKERS /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/schedule-amdgpu-tracker-physreg-crash.ll

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/119690