[CMake] Replace `TARGET_TRIPLE` with `TOOLCHAIN_TARGET_TRIPLE` for Win-to-Arm...

[CMake] Replace `TARGET_TRIPLE` with `TOOLCHAIN_TARGET_TRIPLE` for Win-to-Arm cross toolchain cache file. NFC.

Avoid using TARGET_TRIPLE argument for the cross toolchain cmake cache file and replace it
with TOOLCHAIN_TARGET_TRIPLE.

Reference: https://reviews.llvm.org/D119918

Differential Revision: https://reviews.llvm.org/D121029