Remove the replace directive and update x/tools.

For golang/go#53823

Change-Id: I78681cfdd84834438d20f3815898b18115e3bf8f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/417414
gopls-CI: kokoro <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Robert Findley <[email protected]>
Reviewed-by: Nooras Saba‎ <[email protected]>