tools/xendomains: Restrict domid pattern in LIST_GREP

tools/xendomains: Restrict domid pattern in LIST_GREP

The xendomains script uses the output of `xl list -l` to collect the
id and name of each domain, which is used in the shutdown logic, amongst
other purposes.

The linked commit added a "domid" field to libxl_domain_create_info.
This causes the output of `xl list -l` to contain two "domid"s per
domain, which may not be equal. This in turn causes `xendomains stop` to
issue two shutdown commands per domain, one of which is to a duplicate
and/or invalid domid.

To work around this, make the LIST_GREP pattern more restrictive for
domid, so it only detects the domid at the top level and not the domid
inside c_info.

Fixes: 4a3a25678d92 ("libxl: allow creation of domains with a specified or random domid")
Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Release-acked-by: Henry Wang <Henry.Wang@arm.com>