gopls/internal/test/integration/workspace: fix broken test

(Semantic conflict between CL 711340 and CL 711320.)

Fixes golang/go#75911

Change-Id: I98960730147c0c548da2660b72b36d80cb010671
Reviewed-on: https://go-review.googlesource.com/c/tools/+/712182
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Alan Donovan <adonovan@google.com>
Reviewed-by: David Chase <drchase@google.com>

Author: adonovan

gopls/internal/test/integration/workspace/standalone_test.go

@@ -29,7 +29,6 @@ type I interface {
 }
 -- lib/ignore.go --
 //go:build ignore
-// +build ignore
 
 package main
 
@@ -164,7 +163,6 @@ go 1.18
 package lib // without this package, files are loaded as command-line-arguments
 -- ignore.go --
 //go:build ignore
-// +build ignore
 
 package main
 
@@ -173,7 +171,6 @@ package main
 func main() {}
 -- standalone.go --
 //go:build standalone
-// +build standalone
 
 package main