mdnsd: Remove domain_deprecated

Remove domain_deprecated from mdnsd. This removes some unnecessarily
permissive rules from mdnsd.

As part of this, re-allow /proc/net access, which is removed as
a result of removing domain_deprecated.

Bug: 25433265
Change-Id: Ie1cf27179ac2e9170cf4cd418aea3256b9534603

mdnsd.te

 # mdns daemon
-type mdnsd, domain, domain_deprecated, mlstrustedsubject;
+type mdnsd, domain, mlstrustedsubject;
 type mdnsd_exec, exec_type, file_type;
 
 init_daemon_domain(mdnsd)
 net_domain(mdnsd)
+
+# Read from /proc/net
+r_dir_file(mdnsd, proc_net)