common/synctest: merge versioned file into synctest.go

common/synctest: fix gofmt formatting

Author: anacrolix

common/synctest/synctest.go

@@ -16,15 +16,11 @@
 
 package synctest
 
-import (
-	"testing"
-	"testing/synctest"
-)
+import "testing/synctest"
 
 //
 // NOTE: we can remove this pkg once go1.26 is out, and we've dropped support for go1.25
 //
 
 var Wait = synctest.Wait // nolint:govet
-
-type testFunc func(t *testing.T, f func(*testing.T))
+var Test = synctest.Test // nolint:govet