CI: Remove Ccache restoration for Windows builds
Once upon a time there was the idea to enable use of Ccache for
Windows builds on CI as well, but to achieve this the project would
need to switch to clang-cl.exe as its compiler and use an additional
post-build step to generate PDBs from binaries.
Using a different compiler for continuous integration than for building
release builds defeats the purpose of CI however, so the idea was
dropped.
PatTheMav