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-client/src/event.rs

@@ -41,7 +41,6 @@ pub enum ClientEvent {
 
     EchoSent {
         seq: u32,
-        logical_seq: u64,
         remote: SocketAddr,
         scheduled_at: Instant,
         sent_at: ClientTimestamp,
@@ -52,7 +51,6 @@ pub enum ClientEvent {
 
     EchoReply {
         seq: u32,
-        logical_seq: u64,
         remote: SocketAddr,
         sent_at: ClientTimestamp,
         received_at: ClientTimestamp,
@@ -66,7 +64,6 @@ pub enum ClientEvent {
 
     EchoLoss {
         seq: u32,
-        logical_seq: u64,
         sent_at: ClientTimestamp,
         timeout_at: std::time::Instant,
     },
@@ -80,7 +77,6 @@ pub enum ClientEvent {
 
     LateReply {
         seq: u32,
-        logical_seq: Option<u64>,
         highest_seen: u32,
         remote: SocketAddr,
         sent_at: Option<ClientTimestamp>,