Don't ip_bracket addresses returned by check_dns.

This ends up in opts['master_ip'] where it can cause problems. I found
this while testng a git+pip based minion installation on Ubuntu Bionic.
I'm not sure why it doesn't affect other targeted OS versions in the
test framework. On Bionic, if 'salt' resolves to an IPv6 address,
zmq fails to connect to the master, and complains about the bracketed
address.

salt/utils/network.py

@@ -1886,14 +1886,14 @@ def dns_check(addr, port, safe=False, ipv6=None):
                 if h[0] == socket.AF_INET6 and ipv6 is False:
                     continue
 
-                candidate_addr = salt.utils.zeromq.ip_bracket(h[4][0])
+                candidate_addr = h[4][0]
 
                 if h[0] != socket.AF_INET6 or ipv6 is not None:
                     candidates.append(candidate_addr)
 
                 try:
                     s = socket.socket(h[0], socket.SOCK_STREAM)
-                    s.connect((candidate_addr.strip('[]'), port))
+                    s.connect((candidate_addr), port))
                     s.close()
 
                     resolved = candidate_addr