container/heap: remove confusing claim of memory leak

The term "memory leak" was misused here, as the memory is still referenced
by the slice.

Fixes #65403

Change-Id: Id102419d4c798fb2a4ec8be86be9ec9b5cdd98e6
GitHub-Last-Rev: 3febcd0
GitHub-Pull-Request: #65404
Reviewed-on: https://go-review.googlesource.com/c/go/+/559775
Auto-Submit: Keith Randall <[email protected]>
Reviewed-by: Mauri de Souza Meneguzzo <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Reviewed-by: Robert Griesemer <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: codesoap

src/container/heap/example_pq_test.go

@@ -45,7 +45,7 @@ func (pq *PriorityQueue) Pop() any {
 	old := *pq
 	n := len(old)
 	item := old[n-1]
-	old[n-1] = nil  // avoid memory leak
+	old[n-1] = nil  // don't stop the GC from reclaiming the item eventually
 	item.index = -1 // for safety
 	*pq = old[0 : n-1]
 	return item