[llvm] [CodeGen] Refactor rematerializer unit tests to reduce boilerplate (NFC) (PR #197575)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-nvptx64-nvidia-win` running on `as-builder-8` while building `llvm` at step 7 "test-build-unified-tree-check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/155/builds/20685

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

```
Step 7 (test-build-unified-tree-check-llvm) failure: test (failure)
...
[845/878] Linking CXX executable unittests\Transforms\IPO\IPOTests.exe
[846/878] Linking CXX executable unittests\tools\llvm-cfi-verify\CFIVerifyTests.exe
[847/878] Linking CXX executable unittests\Analysis\AnalysisTests.exe
[848/878] Linking CXX executable unittests\Frontend\LLVMFrontendTests.exe
[849/878] Linking CXX executable bin\LLJITWithThinLTOSummaries.exe
[850/878] Linking CXX executable bin\OrcV2CBindingsAddObjectFile.exe
[851/878] Linking CXX executable bin\OrcV2CBindingsRemovableCode.exe
[852/878] Linking CXX executable unittests\CodeGen\CGPluginTest\CGPluginTest.exe
[853/878] Linking CXX executable unittests\Transforms\Coroutines\CoroTests.exe
[854/878] Building CXX object unittests\CodeGen\CMakeFiles\CodeGenTests.dir\RematerializerTest.cpp.obj
FAILED: unittests/CodeGen/CMakeFiles/CodeGenTests.dir/RematerializerTest.cpp.obj 
C:\ninja\ccache.exe C:\PROGRA~1\MICROS~2\2022\COMMUN~1\VC\Tools\MSVC\1444~1.352\bin\Hostx64\x64\cl.exe  /nologo /TP -DLLVM_BUILD_STATIC -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_GLIBCXX_ASSERTIONS -D_HAS_EXCEPTIONS=0 -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_EXTENSIVE -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -IC:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\unittests\CodeGen -IC:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\llvm\unittests\CodeGen -IC:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\include -IC:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\llvm\include -IC:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\third-party\unittest\googletest\include -IC:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\third-party\unittest\googlemock\include /DWIN32 /D_WINDOWS   /Zc:inline /Zc:preprocessor /Zc:__cplusplus /Oi /bigobj /permissive- /W4 -wd4146 -wd4244 -wd4267 -wd4456 -wd4457 -wd4458 -wd4459 -wd4624 -wd4100 -wd4127 -wd4505 -wd4702 -wd4245 -wd4310 -wd4701 -wd4703 -wd4389 -wd4805 -wd4577 -wd4319 -wd4324 -wd4251 -wd4275 -w14062 -we4238 /Gw /O2 /Ob2  -MD -UNDEBUG /EHs-c- /GR- -std:c++17 /showIncludes /Founittests\CodeGen\CMakeFiles\CodeGenTests.dir\RematerializerTest.cpp.obj /Fdunittests\CodeGen\CMakeFiles\CodeGenTests.dir\ /FS -c C:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\llvm\unittests\CodeGen\RematerializerTest.cpp
C:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\llvm\unittests\CodeGen\RematerializerTest.cpp(96): error C3861: 'LLVMInitializeAMDGPUTargetInfo': identifier not found
C:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\llvm\unittests\CodeGen\RematerializerTest.cpp(97): error C3861: 'LLVMInitializeAMDGPUTarget': identifier not found
C:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\llvm\unittests\CodeGen\RematerializerTest.cpp(98): error C3861: 'LLVMInitializeAMDGPUTargetMC': identifier not found
[855/878] Linking CXX executable unittests\Transforms\Instrumentation\InstrumentationTests.exe
[856/878] Linking CXX executable unittests\Transforms\Utils\UtilsTests.exe
[857/878] Linking CXX executable unittests\DebugInfo\DWARF\DebugInfoDWARFTests.exe
[858/878] Building CXX object unittests\ObjectYAML\CMakeFiles\ObjectYAMLTests.dir\DXContainerYAMLTest.cpp.obj
[859/878] Linking CXX executable unittests\MI\MITests.exe
[860/878] Linking CXX executable unittests\Target\TargetMachineCTests.exe
[861/878] Linking CXX executable unittests\tools\llvm-mca\LLVMMCATests.exe
[862/878] Linking CXX executable unittests\MIR\MIRTests.exe
[863/878] Linking CXX executable bin\Kaleidoscope-Ch4.exe
[864/878] Linking CXX executable bin\Kaleidoscope-Ch6.exe
[865/878] Linking CXX executable bin\Kaleidoscope-Ch5.exe
[866/878] Linking CXX executable unittests\CodeGen\GlobalISel\GlobalISelTests.exe
[867/878] Linking CXX executable bin\Kaleidoscope-Ch7.exe
[868/878] Linking CXX executable unittests\ExecutionEngine\Orc\OrcJITTests.exe
[869/878] Linking CXX executable unittests\Passes\PassBuilderBindings\PassesBindingsTests.exe
[870/878] Linking CXX executable unittests\tools\llvm-exegesis\LLVMExegesisTests.exe
[871/878] Linking CXX executable unittests\Transforms\Scalar\ScalarTests.exe
[872/878] Linking CXX executable unittests\Target\X86\X86Tests.exe
[873/878] Linking CXX executable unittests\DebugInfo\LogicalView\DebugInfoLogicalViewTests.exe
[874/878] Linking CXX executable unittests\IR\IRTests.exe
[875/878] Linking CXX executable unittests\ExecutionEngine\MCJIT\MCJITTests.exe
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/197575