gms/gossiper: Cleanup convict()
gms/gossiper: Cleanup convict()

Have convict() use get_endpoint_state_for_endpoint_ptr(), simplify
logging, and also protect expensive operations by checking the log
level.

Signed-off-by: Duarte Nunes <a60e8b7496f7715d71354fe4c06dd24017025bf1@scylladb.com>

scylladb/scylla,avikivity/scylla,duarten/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,duarten/scylla,scylladb/scylla,avikivity/scylla,duarten/scylla