slices: zero the slice elements discarded by Delete, DeleteFunc, Compact, CompactFunc, Replace.
To avoid memory leaks in slices that contain pointers, clear the elements between the new length and the original length.
Fixes #63393
Change-Id: Ic65709726f4479d70c6bce14aa367feb753d41da
Reviewed-on: https://go-review.googlesource.com/c/go/+/541477 Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Keith Randall <khr@golang.org> Reviewed-by: Keith Randall <khr@golang.org>