Fix potential bugs that may cause resolver to retry endlessly

[1] If DNS-over-TLS validation success, but server does not
respond to DNS-over-TLS query after a while (the server can still
respond to DNS-over-UDP). Then, query a non-exist domain.

[2] If DNS-over-TLS validation success, but server does not
respond to DNS-over-TLS query after a while. Also, the server always
responds RCODE=RES_F_EDNS0ERR on DNS-over-UDP.

These strange network behaviors should not happen. However, once they
happen (maybe by bogus servers), the resolver should be able to handle
it gracefully.

Bug: 120910570
Test: runtests.sh pass
Change-Id: I7e3044e012303a7991b04e7d38e55340e2a5db1a