This PR contains two patches which get rid of unnecessary sleeps on cql_test_env teardown greatly reducing run time of tests.
Reduces run time of `build/dev/test/boost/schema_change_test` from 90s to 6s.
Closesscylladb/scylladb#16111
* github.com:scylladb/scylladb:
test: cql_test_env: Interrupt all components on cql_test_env teardown
tests: cql_test_env: Skip gossip shutdown sleep