MDEV-32363 Shut down Galera networking and logging on fatal signal

[temeo]

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• [x] The Jira issue number for this PR is: MDEV-32363

Description

When handling fatal signal, shut down Galera networking before printing out stack trace and writing core file. This is to achieve fail-silent semantics on crashes which may keep the process running for a long time, but not fully responding e.g. due to core dumping or symbol resolving.

Also suppress all Galera/wsrep logging to avoid logging from background threads to garble crash information from signal handler.

Notice that for fully fail-silent crash, Galera 26.4.19 is needed.

How can this PR be tested?

Deterministic test case does not exist. In order to test, start a 3 node cluster and kill one of the nodes by kill -SIGABRT. Observe that the killed node logs

WSREP: Suppressing further logging
WSREP: Shutting down network communications

before printing out stacktrace. Other nodes should report lost connection almost immediately.

Basing the PR against the correct MariaDB version

• [ ] This is a new feature or a refactoring, and the PR is based against the latest MariaDB development branch.
• [x] This is a bug fix, and the PR is based against the earliest maintained branch in which the bug can be reproduced.

PR quality check

• [x] I checked the CODING_STANDARDS.md file and my PR conforms to this where appropriate.
• [x] For any trivial modifications to the PR, I am ok with the reviewer making the changes themselves.

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[sysprg]

Thanks, the fix has been merged with the head revision: https://github.com/MariaDB/server/commit/54a10a429334a9579558a5d284c510d6f8b5bc97