EXECUTIVE SUMMARY
=================

This worklog reclassifies some Group Replication as system messages.
System messages are always logged, independently of the server log
level.
After this work is done, operator can always do a post observation
of the main events on group lifetime.

RATIONALE
=========

Currently the default MySQL log level[1] is 2, that is, only log
messages from levels SYSTEM, ERROR and WARNING are logged, while
INFORMATION level log messages are skipped.
Some Group Replication status messages are logged with INFORMATION
([Note]) level, which means that those messages are not logged by
default.
One of these examples is:
  [Note] [MY-011503] [Repl] Plugin group_replication reported: \
  'Group membership changed to 10.0.0.1:33061, 10.0.0.2:33061, \
  10.0.0.3:33061 on view 15760832593961450:3.'

This worklog will reclassify all important INFORMATION log messages
to SYSTEM[2] log level, making them always present on the server
error log.

[1] https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_log_error_verbosity
[2] https://dev.mysql.com/doc/dev/mysql-server/latest/my__loglevel_8h.html

ReviewBoard: 23855