Buffered error logging for Server error log

Introduction

Currently MariaDB error log is written in sql/log.cc function print_buffer_to_file() function that uses static buffer with size 1024 bytes. Every error message is written to file immediately. Function also uses mutex LOCK_error_log making error logging single threaded.

Solution

MariaDB error logging should use buffered logging similar to what Audit Plugin uses (ref : MDEV-34680).

Summary of changes

Buffered Logging:

If user has requested buffered logging final logging happens at logger service that implements an in-memory buffer to reduce disk I/O by batching log writes.

Dynamic Buffer Management:

Add log_buffer_size system variable for user-customizable flushing based on data volume, adapting to varying workloads.

Galera error logging:

If configured should use same error logging interface and debug messages also if user has so requested.

Confirm Performance Improvement: