remove unused test funcs

src/util/limited_queue.rs

@@ -48,11 +48,6 @@ impl<T, const N: usize> LimitedQueue<T, N> {
         self.len += usize::from(self.len < N);
     }
 
-    #[cfg(test)]
-    pub const fn is_empty(&self) -> bool {
-        self.len == 0
-    }
-
     pub const fn is_full(&self) -> bool {
         self.len == N
     }
@@ -61,15 +56,6 @@ impl<T, const N: usize> LimitedQueue<T, N> {
         self.len
     }
 
-    #[cfg(test)]
-    pub const fn last(&self) -> Option<&T> {
-        if self.is_empty() {
-            None
-        } else {
-            Some(&self.queue[self.end])
-        }
-    }
-
     pub fn as_slices(&self) -> (&[T], &[T]) {
         if self.is_full() {
             (&self.queue[self.end + 1..N], &self.queue[0..=self.end])