cmd/vendor: update x/tools and x/text

This CL updates x/tools to 68e94bd and x/text to v0.24.0,
updates the vendor tree, and re-runs the bundle step for net/http.

Updates golang/go#28308

Change-Id: I4184f77547f535270ddc8e2ce6542377e3046ffd
Reviewed-on: https://go-review.googlesource.com/c/go/+/667597


LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>