Bug #93212 Some threads are not registered in the global thread manager

Description:

After code inspection it was reported that some threads that execute transient or minor tasks in group replication are not registered in the global thread manager.

Such examples include the:
The delayed initialization thread in delayed_plugin_initialization.cc
The group partition thread in group_partition_handling.cc
other might exists.

With no major implications as of now, this should be fixed to avoid issues on global thread monitorization or similar issues.

How to repeat:
Look for mysql_thread_create inside the group replication source directory
Check from these threads the ones that are registered and the ones that aren't

Suggested fix:
Register all threads using  global_thd_manager_add_thd

Posted by developer:
 
Changelog entry added for MySQL 8.0.18:

Some threads that executed transient or minor Group Replication tasks, such as the delayed plugin initialization thread, were not visible in the Performance Schema threads table.