CUDA build fixes and nvcc warning cleanup

[debog]

Fixes four CUDA build failures and warning sources found on LLNL LC Matrix (nvcc 13.1.1, ERF_ENABLE_TESTS=ON), plus the report-gate pattern that hid them. Each failure masked the next, so they surfaced serially after #3548.

• Tests/CMakeLists.txt: compile the six test-helper executables via setup_target_for_cuda_compilation(). They link AMReX::amrex and include the generated AMReX_Config.H, so AMREX_USE_CUDA is defined and AMReX_GpuReduce.H requires <cub/cub.cuh>; built as plain CXX they receive no CUDA include path and fail. Latent since Add native SHOC state-update regression coverage #3492 added Tests/ShocPlotfileCheck.cpp, and invisible upstream because ERF_ENABLE_TESTS defaults to OFF and cuda-ci.yml does not set it.
• Tests/Unit/Microphysics/SatAdj/ERF_GTestSatAdjTemperatureDiagnostics.cpp: move the ParallelFor into a free function. nvcc rejects an extended __device__ lambda whose enclosing function has private class access, which googletest's TestBody always has. Introduced by Cloud Chamber initialization, wall fluxes, and budgets - Stage 1 #3527; currently failing cuda-ci.yml on development.
• Source/Microphysics/{SAM,Kessler,Morrison,WSM6,SuperDropletsMoist}: add using NullMoist::Update_Micro_Vars;. Cloud Chamber initialization, wall fluxes, and budgets - Stage 1 #3527 added a second Update_Micro_Vars(MultiFab&, const MultiFab*) overload to NullMoist; classes overriding only the single-argument form hide it, emitting nvcc #611-D roughly 700 times per build. Dispatch is unchanged. Support reference-state thermodynamics in anelastic microphysics #3564 covers all of these except SuperDropletsMoist by overriding both overloads.
• Source/TimeIntegration/ERF_SlowRhsPre.cpp: remove the dead z_t (#550-D), unused since Fix problem of omega not having enough ghost cells when used in creat… #3342.
• .github/workflows/cuda-ci.yml: the report gate greps warning:|error:, which never matches nvcc's warning #NNN-D:. Run 31113179047 at 1ecf606ea logged 818 #611-D diagnostics and reported Warnings: 1.

[pressel]

@debog, thanks for the fixes.