install-deps: save and restore user's XDG_CACHE_HOME

install-deps: save and restore user's XDG_CACHE_HOME

Since ccache 4.0, ccache use $XDG_CACHE_HOME/ccache to keep compile cache
if XDG_CACHE_HOME is set. In this case $XDG_CACHE_HOME is overwrite,
ccache will use $XDG_CACHE_HOME/ccache(ccache will create the dir if not exsit) to
store compile cache, but $XDG_CACHE_HOME will be removed next round running,
leading to ccache contests are always removed. So save and restore user's XDG_CACHE_HOME.

Fixes: https://tracker.ceph.com/issues/65175
Signed-off-by: luo rixin <luorixin@huawei.com>