rpc: Add unit test for cancel connection attempt
rpc: Add unit test for cancel connection attempt

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

syuu1228/seastar,kjniemi/seastar,kjniemi/seastar,scylladb/seastar,scylladb/seastar,kjniemi/seastar,avikivity/seastar,cloudius-systems/seastar,syuu1228/seastar,avikivity/seastar,avikivity/seastar,dreamsxin/seastar,scylladb/seastar,syuu1228/seastar,cloudius-systems/seastar,dreamsxin/seastar,cloudius-systems/seastar,dreamsxin/seastar