Make the gobuild tests work better when running them directly

test/handler/test_gobuild_handler.vader

@@ -28,7 +28,7 @@ Execute (The gobuild handler should handle names with spaces):
   \ ]), 'v:val[1:4]')
 
 Execute (The gobuild handler should handle relative paths correctly):
-  :e! /foo/bar/baz.go
+  silent file! /foo/bar/baz.go
 
   AssertEqual
   \ [
@@ -39,6 +39,6 @@ Execute (The gobuild handler should handle relative paths correctly):
   \     'type': 'E',
   \   },
   \ ],
-  \ ale_linters#go#gobuild#Handler(bufnr('$'), [
+  \ ale_linters#go#gobuild#Handler(bufnr(''), [
   \   'baz.go:27: missing argument for Printf("%s"): format reads arg 2, have only 1 args',
   \ ])