Remove the replace directive and update x/tools.

For golang/go#52213

Change-Id: I0c49b68968c69c97194a7b6ee063a6eed0624074
Reviewed-on: https://go-review.googlesource.com/c/tools/+/398816
Trust: Robert Findley <[email protected]>
Run-TryBot: Robert Findley <[email protected]>
gopls-CI: kokoro <[email protected]>
Reviewed-by: Peter Weinberger <[email protected]>