Motivation:

There was a report from LY internally where DNS resolver warns for `NXDomain`.
```
java.util.concurrent.CompletionException: java.lang.IllegalArgumentException: Empty label is not a legal name
	at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:315)
        ...
	at com.linecorp.armeria.internal.client.dns.SearchDomainDnsResolver.resolve0(SearchDomainDnsResolver.java:99)
	at com.linecorp.armeria.internal.client.dns.SearchDomainDnsResolver.resolve(SearchDomainDnsResolver.java:88)
	at com.linecorp.armeria.internal.client.dns.HostsFileDnsResolver.resolve(HostsFileDnsResolver.java:130)
	at com.linecorp.armeria.internal.client.dns.DefaultDnsResolver.resolveOne(DefaultDnsResolver.java:89)
	at com.linecorp.armeria.internal.client.dns.DefaultDnsResolver.resolve(DefaultDnsResolver.java:81)
	at com.linecorp.armeria.client.endpoint.dns.DnsEndpointGroup.sendQueries(DnsEndpointGroup.java:155)
	at com.linecorp.armeria.client.endpoint.dns.DnsEndpointGroup.lambda$sendQueries$3(DnsEndpointGroup.java:173)
       ...
Caused by: java.lang.IllegalArgumentException: Empty label is not a legal name
  at java.base/java.net.IDN.toASCIIInternal(IDN.java:284)
  at java.base/java.net.IDN.toASCII(IDN.java:123)
  at java.base/java.net.IDN.toASCII(IDN.java:152)
  at com.linecorp.armeria.internal.client.dns.DnsQuestionWithoutTrailingDot.<init>(DnsQuestionWithoutTrailingDot.java:53)
  at com.linecorp.armeria.internal.client.dns.DnsQuestionWithoutTrailingDot.of(DnsQuestionWithoutTrailingDot.java:48)
  at com.linecorp.armeria.internal.client.dns.SearchDomainDnsResolver$SearchDomainQuestionContext.newQuestion(SearchDomainDnsResolver.java:190)
  at com.linecorp.armeria.internal.client.dns.SearchDomainDnsResolver$SearchDomainQuestionContext.nextQuestion0(SearchDomainDnsResolver.java:177)
  at com.linecorp.armeria.internal.client.dns.SearchDomainDnsResolver$SearchDomainQuestionContext.nextQuestion(SearchDomainDnsResolver.java:150)
  at com.linecorp.armeria.internal.client.dns.SearchDomainDnsResolver.lambda$resolve0$1(SearchDomainDnsResolver.java:103)
  ... 19 common frames omitted
```

The NX domain has with a trailing dot and search domains starts with
`.`. As a result, `example.com..search.domain` was made and rejected by `java.net.IDN`

Modifications:

- Remove a leading dot from the normalized search domains.
- Infix a dot when a hostname does not have a trailing dot.

Result:

DNS resolver now correctly adds search domains for hostnames with trailing dots.

… into trailing-dot-searchdomain

- Stop to send queries with search domains when it was resovled.
- Fix a bug where the original hostname was sent as the last query
  when the number of dots in a hostname >= `ndots`.
- Explicitly set `ResolvedAddressTypes.IPV4_ONLY` to avoid flakyness.