Revert "[Offload][AMDGPU] LLVM_ENABLE_RUNTIMES=flang-rt for amdgpu-offload-*" (#130274)

Reverts #129692

The builder amdgpu-offload-rhel-8-cmake-build-only fails because its
version of Ninja is too old. At least Ninja 1.10 is required for its
support for dependencies between Fortran modules.

https://lab.llvm.org/buildbot/#/builders/204/builds/2696

Author: Meinersbur

offload/cmake/caches/AMDGPUBot.cmake

@@ -10,7 +10,7 @@ set(CMAKE_C_COMPILER_LAUNCHER ccache CACHE STRING "")
 set(CMAKE_CXX_COMPILER_LAUNCHER ccache CACHE STRING "")
 
 set(LLVM_ENABLE_PROJECTS "clang;lld;mlir;flang" CACHE STRING "")
-set(LLVM_ENABLE_RUNTIMES "compiler-rt;openmp;offload;flang-rt" CACHE STRING "")
+set(LLVM_ENABLE_RUNTIMES "compiler-rt;openmp;offload" CACHE STRING "")
 
 set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR ON CACHE BOOL "")
 set(LLVM_ENABLE_ASSERTIONS ON CACHE BOOL "")