Re-apply changeset from (PR) #58835, which was reverted in (PR) #58872 due to (issue) #58918.

Since the issue is primarily "cosmetic" (wrong limit value in system.settings, but it's actually applied) and (PR) #59018 is still a draft, I rewrote an offending test, so it is not blocking and maybe we can still include it in 24.1.

Original description from (PR) #58835:

Resolves #58553

Allows to use the following settings via MySQL interface:

SET NET_WRITE_TIMEOUT = X;
SET NET_READ_TIMEOUT = Y;

net_write_timeout is translated into the native send_timeout ClickHouse setting and, similarly, net_read_timeout into receive_timeout. These statements work regardless of the input query being upper or lower case.

Additionally, fixed an issue where changing MySQL SQL_SELECT_LIMIT setting was possible only if the entire statement was in upper case.

Changelog category (leave one):

• Improvement

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

MySQL interface gained support for net_write_timeout and net_read_timeout settings. net_write_timeout is translated into the native send_timeout ClickHouse setting and, similarly, net_read_timeout into receive_timeout. Fixed an issue where it was possible to set MySQL sql_select_limit setting only if the entire statement was in upper case.