[DFSan] Replace `cat` with `cmake -E cat` (#90557)
`CMake` supports [this
command](https://cmake.org/cmake/help/latest/manual/cmake.1.html#cmdoption-cmake-E-arg-cat)
as of version 3.18. [D151344](https://reviews.llvm.org/D151344) bumped
the minimum version to 3.20, so, it is now possible to remove the
dependency on the external utility. This helps to cross-compile from
Windows to Linux without installing additional tools, such as MSYS2.
