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/client/tests/sequence.rs

@@ -26,7 +26,6 @@ fn sequence_ordering_handles_normal_and_wrapped_values() {
 fn highest_received_seq_updates_across_wrap() {
     let mut session = ActiveSession {
         next_wire_seq: 0,
-        next_logical_seq: 0,
         highest_received_seq: Some(u32::MAX),
         packets_sent: 0,
         start_mono: Instant::now(),