24.3 Backport of #69582 - more advanced SSL options for Keeper internal communication

[Enmk]

Changelog category (leave one):

• Improvement

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

Support more advanced SSL options for Keeper's internal communication (e.g. private keys with passphrase) (ClickHouse#69582 by @antonio2368)

[altinity-robot]

This is an automated comment for commit 81249e1 with description of existing statuses. It's updated for the latest CI running

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Check name	Description	Status
CI running	A meta-check that indicates the running CI. Normally, it's in success or pending state. The failed status indicates some problems with the PR	⏳ pending
ClickHouse build check	Builds ClickHouse in various configurations for use in further steps. You have to fix the builds that fail. Build logs often has enough information to fix the error, but you might have to reproduce the failure locally. The cmake options can be found in the build log, grepping for cmake. Use these options and follow the general build process	⏳ pending
Docker keeper image	The check to build and optionally push the mentioned image to docker hub	❌ failure
Integration tests	The integration tests report. In parenthesis the package type is given, and in square brackets are the optional part/total tests	❌ failure
Mergeable Check	Checks if all other necessary checks are successful	❌ failure
Stateless tests	Runs stateless functional tests for ClickHouse binaries built in various configurations -- release, debug, with sanitizers, etc	❌ failure
Stress test	Runs stateless functional tests concurrently from several clients to detect concurrency-related errors	❌ failure

Successful checks

Check name	Description	Status
Compatibility check	Checks that clickhouse binary runs on distributions with old libc versions. If it fails, ask a maintainer for help	✅ success
Docker server image	The check to build and optionally push the mentioned image to docker hub	✅ success
Install packages	Checks that the built packages are installable in a clear environment	✅ success
Ready for release	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	✅ success
Stateful tests	Runs stateful functional tests for ClickHouse binaries built in various configurations -- release, debug, with sanitizers, etc	✅ success

[Enmk]

In 24.3 we are still using BoringSSL, so the error message is a bit different:
OpenSSLException: EVPKey::loadKey(string): error:0900006e:PEM routines:OPENSSL_internal:NO_START_LINE