Increase pool size changes were recently reverted because of the flakiness for the test_gossip_boot test. Test started
to fail on adding the node to the cluster without any issues in the Scylla log file. In test logs it looked like the
installation process for the new node just hanged. After investigating the problem, I've found out that the issue is that
test.py was draining the io_executor pool for cleaning the directory during install that was set to eight workers. So
to fix the issue, io_executor pool should be increased to more or less the same ratio as it was: doubled cluster pool size.
Closesscylladb/scylladb#20276