[clang][deps] NFC: Clean up wording (ignored vs minimized)

The filesystem used during dependency scanning does two things: it caches file entries and minimizes source file contents. We use the term "ignored file" in a couple of places, but it's not clear what exactly that means. This commit clears up the semantics, explicitly spelling out this relates to minimization.

GitOrigin-RevId: 12eafd944e0ffccae93402ddbe2855beb7a939ff
4 files changed