dns/dnsmasq: do not use --dnssec-proxy by default

dnsmasq since 2.80 properly forwards all incoming queries with DO bit
set. That ensures even if the dnsmasq does not do validation, it will
always serve all DNSSEC records if the upstream server provides them.
Regardless local validation is enabled or disabled, it will always offer
all data required for validation to its clients.
But does not set AD bit on local responses unless it did the actual
validation itself.

In case users trust their connection to validating DNS server, they
would have to declare it by adding dnssec-proxy option to dnsmasq conf.d
directory. Because there is no negated no-dnssec-proxy, it cannot be
turned off. I think there is no good reason to be on for all cases and
it would be possible to enable it if still wanted. Move the decision to
the user.

That makes it conform with RFC 4035, paragraph 3.2.3.

Signed-off-by: Petr Menšík <pemensik@redhat.com>

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1639

src/core/dns/nm-dns-dnsmasq.c

@@ -527,7 +527,6 @@ _gl_pid_spawn_next_step(void)
     argv[argv_idx++] = "--cache-size=400";
     argv[argv_idx++] = "--clear-on-reload";     /* clear cache when dns server changes */
     argv[argv_idx++] = "--conf-file=/dev/null"; /* avoid loading /etc/dnsmasq.conf */
-    argv[argv_idx++] = "--proxy-dnssec";        /* Allow DNSSEC to pass through */
     argv[argv_idx++] = "--enable-dbus=" DNSMASQ_DBUS_SERVICE;
 
     /* dnsmasq exits if the conf dir is not present */