Add DNSPolicy health check tests

[averevki]

Test cases:

• Healthy endpoint with TLS
• Healthy endpoint without TLS
• Unhealthy endpoint
• Endpoint removal and return

Also added classes for the health check section of the DNSPolicy and for the DNSHealthCheckProbe CR

Part of the #572

[trepel]

It looks good to me and it (more or less) worked yesterday for me, but today with a new Kuadrant nightly build it does not work. The reason is that DNSPolicy keeps being successfully enforced despite failing health_check. So this piece:

    assert dns_policy.wait_until(has_condition("Enforced", "False"))
    assert dns_policy.wait_until(
        has_record_condition("Ready", "False", "HealthChecksFailed", "None of the healthchecks succeeded")
    )

is never true. Not sure if there has been any changes related to this behavior recently and whether it is intended or not but it seems like a bug to me.

[trepel]

It happened to me twice that I got following error:

testsuite/kuadrant/policy/dns.py:99: in get_dns_health_probe
    dns_probe = self.get_owned("dnsrecords.kuadrant.io")[0].get_owned("DNSHealthCheckProbe")[0]
E   IndexError: list index out of range

As if the resource has not been created yet or ownership relationship has not been established quickly enough. I don't think this is something to fix in this PR - we'll see in nightlies whether this is worth investigating or not.

[averevki]

It happened to me twice that I got following error:

testsuite/kuadrant/policy/dns.py:99: in get_dns_health_probe
    dns_probe = self.get_owned("dnsrecords.kuadrant.io")[0].get_owned("DNSHealthCheckProbe")[0]
E   IndexError: list index out of range

As if the resource has not been created yet or ownership relationship has not been established quickly enough. I don't think this is something to fix in this PR - we'll see in nightlies whether this is worth investigating or not.

It's a bug where if any subdomain in the hostname starts with a number, the dnsoperator won't generate a health probe object for this endpoint. So if testsuite, for example, will generate hostname.123abc.app-services.net hostname for the this test, then test will fail. It is a known issue and I'm waiting for it to get resolved