Fix YAML integration tests

[alesapin]

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[alexey-milovidov]

Why it's needed?

[alesapin]

Because YAML configs doesn't have root tag. We just hardcoded "clickhouse" in YAMLParser

ClickHouse/src/Common/Config/YAMLParser.cpp

Line 159 in dbff8fd

Poco::AutoPtr<Poco::XML::Element> root_node = xml->createElement("clickhouse");

. In integration tests we have several "predefined" configs, like

ClickHouse/tests/integration/helpers/0_common_instance_config.xml

Lines 1 to 20 in dbff8fd

	<yandex>
	<timezone>Europe/Moscow</timezone>
	<listen_host>0.0.0.0</listen_host>
	<custom_settings_prefixes>custom_</custom_settings_prefixes>
	<path>/var/lib/clickhouse/</path>
	<tmp_path>/var/lib/clickhouse/tmp/</tmp_path>
	<!-- For tests which check compatibility with older versions. -->
	<users_config>users.xml</users_config>
	<logger>
	<level>trace</level>
	<log>/var/log/clickhouse-server/clickhouse-server.log</log>
	<errorlog>/var/log/clickhouse-server/clickhouse-server.err.log</errorlog>
	<size>1000M</size>
	<count>10</count>
	<stderr>/var/log/clickhouse-server/stderr.log</stderr>
	<stdout>/var/log/clickhouse-server/stdout.log</stdout>
	</logger>
	</yandex>

. In this configs we have <yandex> root tag. So when we try to run any test with YAML config we will be unable to start clickhouse (root tag mismatch). This parameter allows to change root tag in these "predefined" configs.

[alesapin]

Only flaky check is important

[nikitamikhaylov]

Only flaky check is important

No flaky integration tests.

[alexey-milovidov]

Fix test rocksdb

It did not help.

[alexey-milovidov]

#29341