build_library: Try to clean up unused stuff

There is some cruft left after grub hashes generation. After the
contents are zipped into archive, they don't need to be around any
more.

Try to remove the rootfs directory after unmounting the
image. disk_util can recreate it again if there is a need for it.

Remove the build directory used for generating ACI images - it's not
needed after successful installation.

build_library/build_image_util.sh

@@ -31,6 +31,7 @@ set_build_symlinks() {
 cleanup_mounts() {
   info "Cleaning up mounts"
   "${BUILD_LIBRARY_DIR}/disk_util" umount "$1" || true
+  rmdir "${1}" || true
 }
 
 delete_prompt() {
@@ -763,5 +764,6 @@ EOF
     pushd "${BUILD_DIR}" >/dev/null
     zip --quiet -r -9 "${BUILD_DIR}/${pcr_policy}" pcrs
     popd >/dev/null
+    rm -rf "${BUILD_DIR}/pcrs"
   fi
 }

build_library/vm_image_util.sh

@@ -512,6 +512,8 @@ install_oem_aci() {
         "${aci_path}" \
         "${VM_TMP_ROOT}/usr/share/oem/flatcar-oem-${oem_aci}.aci" ||
     die "Could not install ${oem_aci} OEM ACI"
+    # Remove aci_dir if building ACI and installing it succeeded
+    rm -rf "${aci_dir}"
 }
 
 # Any other tweaks required?