Remove the replace directive and update x/tools.

For golang/go#61926

Change-Id: I80f8f58592f06aba3a91896959fc2481ca3fc563
Reviewed-on: https://go-review.googlesource.com/c/tools/+/518377
Run-TryBot: Robert Findley <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
gopls-CI: kokoro <[email protected]>
Reviewed-by: Peter Weinberger <[email protected]>