Revert unnecessary dependency to fs_config_dirs and fs_config_files

fs_config_dirs and fs_config_files are now correctly built even when we
build the vendor.img only. Therefore, reverting the old trick to force
build them.

Bug: 36071012
Bug: 36070427
Test: m -j 80 vendorimage creates fs_config_dirs and fs_config_files in
/vendor/etc

Change-Id: Ia69761ee25dae71650b8ccf3bcda16abfbd725f6