clientv3: timeouts doesn't work with --user key

[idonin]

etcdctl version: 3.1.2
API version: 3.1

Error:
When passing --user username:password on etcdctl command, timeount doesn't work at all

How to reproduce:

1. Stop etcd node
2. Run ETCDCTL_API=3 etcdctl --user foo:bar get /

What I see:
Hangs on. Permanent loop with this messages in strace

futex(0x1148ab0, FUTEX_WAIT, 0, NULL)   = 0
futex(0x1148ab0, FUTEX_WAIT, 0, NULL)   = -1 EAGAIN (Resource temporarily unavailable)
epoll_wait(4, {}, 128, 0)               = 0` in strace

What expected:
Failing with Error: grpc: timed out when dialing after timeout

Additional:

• With another clients like confd problem may exist, but not checked.
• Another commands like watch, put also affected

[heyitsanthony]

also broken on master