Remove the replace directive and update x/tools.

For golang/go#61675

Change-Id: I2158fbdfa1688b203847a0fea029c64851faa485
Reviewed-on: https://go-review.googlesource.com/c/tools/+/514817
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Peter Weinberger <pjw@google.com>