24.7 add missing documentation and testing

[fm4v]

• accept_invalid_certificate in client config: additional testing
• Add missing documentation for groupConcat after series of reverts and merges
• Add groupConcat to fuzzer

Changelog category (leave one):

• Not for changelog (changelog entry is not required)

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

...

Documentation entry for user-facing changes

• Documentation is written (mandatory for new features)

Information about CI checks: https://clickhouse.com/docs/en/development/continuous-integration/

CI Settings (Only check the boxes if you know what you are doing):

• Allow: All Required Checks
• Allow: Stateless tests
• Allow: Stateful tests
• Allow: Integration Tests
• Allow: Performance tests
• Allow: All Builds
• Allow: batch 1, 2 for multi-batch jobs
• Allow: batch 3, 4, 5, 6 for multi-batch jobs

---

• Exclude: Style check
• Exclude: Fast test
• Exclude: All with ASAN
• Exclude: All with TSAN, MSAN, UBSAN, Coverage
• Exclude: All with aarch64, release, debug

---

• Do not test
• Woolen Wolfdog
• Upload binaries for special builds
• Disable merge-commit
• Disable CI cache

[robot-clickhouse]

This is an automated comment for commit d4537d9 with description of existing statuses. It's updated for the latest CI running

❌ Click here to open a full report in a separate page

Check name	Description	Status
Upgrade check	Runs stress tests on server version from last release and then tries to upgrade it to the version from the PR. It checks if the new server can successfully startup without any errors, crashes or sanitizer asserts	❌ failure

Successful checks

Check name	Description	Status
Builds	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	✅ success
Docs check	Builds and tests the documentation	✅ success
Fast test	Normally this is the first check that is ran for a PR. It builds ClickHouse and runs most of stateless functional tests, omitting some. If it fails, further checks are not started until it is fixed. Look at the report to see which tests fail, then reproduce the failure locally as described here	✅ success
Flaky tests	Checks if new added or modified tests are flaky by running them repeatedly, in parallel, with more randomization. Functional tests are run 100 times with address sanitizer, and additional randomization of thread scheduling. Integration tests are run up to 10 times. If at least once a new test has failed, or was too long, this check will be red. We don't allow flaky tests, read the doc	✅ success
Integration tests	The integration tests report. In parenthesis the package type is given, and in square brackets are the optional part/total tests	✅ success
Style check	Runs a set of checks to keep the code style clean. If some of tests failed, see the related log from the report	✅ success
Unit tests	Runs the unit tests for different release types	✅ success

[nikitamikhaylov]

Good catch, but, unfortunately it is used by OSSFuzz, not by our fuzzers (because they are AST-based, and can grab all the information from inside the codebase).