Fixes: #12286 radosgw-admin: after subuser modify print only once user info.

Fixes: #12286 radosgw-admin: after subuser modify print only once user info.
remove rgw_admin.cc OPT_SUBUSER_MODIFY, show_user_info code block.

switch (opt_cmd) {
...
case OPT_SUBUSER_MODIFY:
show_user_info(info, formatter);       //show first time (remove this)
break;
...
}

// output the result of a user operation
if (output_user_info) {
...
show_user_info(info, formatter);       //show second time
}

test fix:
before: after subuser modify print twice user info.
after changes, do the same procedure, print only once user info.

Signed-off-by: guce guce@h3c.com
(cherry picked from commit c604dd97fc179e5c2f640818c0f6e7cf99701947)