CI: Disable caching on FreeBSD

It didn't quite work, now it started failing altogether.

.github/workflows/ci.yml

@@ -258,11 +258,6 @@ jobs:
       # Required for the rust-cache action to work.
       - uses: dtolnay/rust-toolchain@stable
 
-      # FIXME: doesn't seem to cache the builds, only the downloads for some unknown reason.
-      - uses: Swatinem/rust-cache@v2
-        with:
-          cache-all-crates: true
-
       # Remove man-db triggers to speed up Ubuntu upgrade by a minute or two during vmactions/freebsd-vm action run.
       - run: |
           sudo rm /var/lib/dpkg/info/man-db.*
@@ -270,6 +265,7 @@ jobs:
       - name: Build
         uses: vmactions/freebsd-vm@966989c456d41351f095a421f60e71342d3bce41  # v1.2.1
         with:
+          copyback: false
           prepare: |
             pkg update -f
             pkg install -y ${{ env.DEPS_PKG }}