LU-15998 pcc: set hsm-root correctly during copytool setup

LU-15998 pcc: set hsm-root correctly during copytool setup

During copytool setup, we set --hsm-root with the archive root
path of $SINGLEAGT. However, when set --hsm-root explicitly via
"-h|--hsm-root", it should reset the hsm root with the specified
one. Otherwise, it will cuase sanity-pcc/test_3b failed.

Test-Parameters: clientcount=3 testlist=sanity-pcc,sanity-pcc,sanity-pcc
Signed-off-by: Qian Yingjin <qian@ddn.com>
Change-Id: Ida6c1ff7459548b068fd62ce315fe8075633b5fc
Signed-off-by: Yang Sheng <ys@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/47909
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>