go/types, types2: consistently write "x | y" rather than "x|y" for unions

go/types, types2: consistently write "x | y" rather than "x|y" for unions

Use the same spacing convention ("x | y") for union terms everythere,
matching the gofmt precedent.

Fixes #53279.

Change-Id: Ic3ccd7433b5f62402ba41cf05a75f9a1d99a8086
Reviewed-on: https://go-review.googlesource.com/c/go/+/410955
Reviewed-by: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>