Backport #17254 to 20.12: Fix \"Unexpected packet Data received from client\"  for Distributed queries

Backport #17248 to 20.12: Fix #15235. When clickhouse-copier handle non-partitioned table, throws segfault error.

Backport #16715 to 20.12: ISSUES-16605 fix without returning affected rows when insert select query in MySQL handler

Since if the connection will be closed (by some reason), then the
setting will not be applied after transparent reconnect (since only
native clickhouse-client can do this, since it parses the query, but
perf tests uses python driver).

Just use inplace SETTINGS clause or <settings>.

Avoid breaking backwards compatibility by default for now.

For now uuids are not generated at all, they are present only if the
part is updated manually (as you can see in the integration test).

The only place where they can be seen today by an end user is in
`system.parts` table. I was looking for hiding this column behind an
option but couldn't find an easy way to do that.

Likely this is also required for WAL, but need to think how not to break
compatibility.

Relates to #13574, https://github.com/ClickHouse/ClickHouse/issues/13574

Next 1: In the upcoming PR the plan is to integrate de-duplication based on
these fingerprints in the query pipeline.

Next 2: We'll enable automatic generation of uuids and come up with a
way for conditionally sending uuids when processing distributed queries
only when part movement is in progress.

Right now due to rotation the archive with the clickhouse-server.log
maybe not full, for example:
- not full - https://clickhouse-test-reports.s3.yandex.net/16947/caf5f98db2ae39dd911f7d1fc0a7c2cc382b1c53/functional_stateless_tests_(ubsan)/clickhouse-server.log (no messages about server start)
- full     - https://clickhouse-test-reports.s3.yandex.net/16993/d1f52dc72d417580c4088cf3880593176416bea2/functional_stateless_tests_(thread).html

And sometimes rotated part may include relative part of the log, so it
is better to disable it.

Sometimes it is odd to get TLD itself from the
cutToFirstSignificantSubdomain() (since you will not get TLD itself if
you pass it directly):
- cutToFirstSignificantSubdomain('org')            -> ""
- cutToFirstSignificantSubdomain('www.org')        -> org
- cutToFirstSignificantSubdomain('kernel.org')     -> kernel.org
- cutToFirstSignificantSubdomain('www.kernel.org') -> kernel.org

So add one more function to get www.org in this case:
- cutToFirstSignificantSubdomainWithWWW('org')            -> ""
- cutToFirstSignificantSubdomainWithWWW('www.org')        -> www.org
- cutToFirstSignificantSubdomainWithWWW('kernel.org')     -> kernel.org
- cutToFirstSignificantSubdomainWithWWW('www.kernel.org') -> kernel.org

P.S. not sure about the naming though, so it will great if someone has
suggestion for the name.

Fixing unstable test in tests/testflows/ldap/external_user_directory/tests/authentications.py