Currently WebKit's os_signposts are only enabled on AppleInternal builds. The idea was that sensitive content might be included in the signposts which should only be logged on internal builds. But this is the wrong way of achieving that goal, as we can use the standard logging privacy specifiers to control content that should be redacted from signposts. This also makes it hard to enable the signposts on perf test bots that emulate standard OS builds.