All compaction task executors, except for regular compaction one,
become task manager compaction tasks.
Creating and starting of major_compaction_task_executor is modified
to be consistent with other compaction task executors.
Closes#14505
* github.com:scylladb/scylladb:
test: extend test_compaction_task.py to cover compaction group tasks
compaction: turn custom_task_executor into compaction_task_impl
compaction: turn sstables_task_executor into sstables_compaction_task_impl
compaction: change sstables compaction tasks type
compaction: move table_upgrade_sstables_compaction_task_impl
compaction: pass task_info through sstables compaction
compaction: turn offstrategy_compaction_task_executor into offstrategy_compaction_task_impl
compaction: turn cleanup_compaction_task_executor into cleanup_compaction_task_impl
comapction: use optional task info in major compaction
compaction: use perform_compaction in compaction_manager::perform_major_compaction