fix(flowcontrol): call up() after down() in maxMinHeap.Remove

Remove swaps position i with the last element then calls down() but
not up(). When the last element comes from a different subtree, the
ancestor relationship can break:

  Before:              After Remove(index=3, time=1):

        0                    0
       / \                  / \
      5   50               5   50
     / \    \             / \
    1   4   40          40   4

  Last element (index 5, time=40) swaps into index 3.
  down(3): no children, no-op.
  Node 1 (min-level, time=5) must be lowest-priority in {5, 40, 4}.
  time=40 has lower priority than time=5 -- heap property violated.

Add the missing up(i) call after down(i). If down moved the element,
up is a no-op at the new position (and vice versa).

Signed-off-by: RishabhSaini <rishabhsaini01@gmail.com>

Author: RishabhSaini

pkg/epp/flowcontrol/framework/plugins/queue/maxminheap.go

@@ -285,9 +285,12 @@ func (h *maxMinHeap) Remove(handle flowcontrol.QueueItemHandle) (flowcontrol.Que
 		delete(h.handles, handle)
 		h.byteSize.Add(^item.OriginalRequest().ByteSize() + 1) // Atomic subtraction
 
-		// The swapped item at index i might violate the heap property, so we must restore it
-		// by bubbling the item down the heap.
+		// The swapped item at index i might violate the heap property in either direction:
+		//   - downward: it is less extreme than its descendants -> down() fixes this.
+		//   - upward:   it is more extreme than its ancestors   -> up() fixes this.
+		// Both calls are needed because the replacement can come from a different subtree.
 		h.down(i)
+		h.up(i)
 	} else {
 		// It's the last item, just remove it.
 		h.items = h.items[:n]