Don't show dead edit links in diff/old revisions

These are just dead anchor links anyway. In diff/old revisions they
are not needed, also not as a placeholder for the JavaScript since
the JavaScript should not run in diff/old revisions anyway. See
I429f44a.

Bug: 72177
Change-Id: I2cd252c4c9b2c6ccabf911ab08d3af46da42bf23