refactor: remove logical_seq from client events, session tracking and stats usage

It was an attempt at handling integer wraparound more cleanly keeping in mind that we have a continuous mode,
and so we can more easily reach seq > u32::MAX

However after running the numbers, if we run with a interval of 10ms, it's still gonna take ~497 days before we hit integer overflow, so for now it doesn't seem worth to have this extra logic to handle something that'll in 99.9% of cases be purely an edge case

Keeping in mind autorate usage, in sqm-autorate-rust each send loop is 500 ms by default, and the sleep is then 500 ms / 5 reflectors, so our interval is 100 ms. that means it'll take 4970 days or ~13.6 years to reach the limit. Not worth dealing with IMO

crates/irtt-cli/src/summary.rs

@@ -229,7 +229,6 @@ mod tests {
 
         collector.process(&ClientEvent::EchoSent {
             seq: 1,
-            logical_seq: 1,
             remote: test_remote(),
             scheduled_at: sent_at.mono,
             sent_at,
@@ -239,7 +238,6 @@ mod tests {
         });
         collector.process(&ClientEvent::EchoReply {
             seq: 1,
-            logical_seq: 1,
             remote: test_remote(),
             sent_at,
             received_at,
@@ -287,7 +285,6 @@ mod tests {
         let received_at = test_timestamp(Duration::from_secs(1) + Duration::from_micros(1500));
         collector.process(&ClientEvent::EchoReply {
             seq: 1,
-            logical_seq: 1,
             remote: test_remote(),
             sent_at: test_timestamp(Duration::from_secs(1)),
             received_at,