Revert "client: support listxattr for quota attributes"

This reverts commit 55413482698c61e877312f1e749c657550965890.

this cause 'cp -a' copies quota setting. It's not the expected behavior in most case

Signed-off-by: Yunchuan Wen <yunchuanwen@ubuntukylin.com>
Reviewed-by: Yan, Zheng <ukernel@gmail.com>
mds: fix parse_quota_vxattr for invalid data

Signed-off-by: Yunchuan Wen <yunchuanwen@ubuntukylin.com>
test: modify cephfs quota test case

Signed-off-by: Yunchuan Wen <yunchuanwen@ubuntukylin.com>