Remove the replace directive and update x/tools.

For golang/go#60917

Change-Id: Ib74ea83cfbe68ee97f3da47353de75b237fcd5c0
Reviewed-on: https://go-review.googlesource.com/c/tools/+/504896
gopls-CI: kokoro <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
Run-TryBot: Robert Findley <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>