lfs: don't skip locally available blobs when verifying The `skipflags` config was introduced in a2ab9ebcd85b, which specifically calls out downloading and storing all blobs as potentially too expensive. But I don't see any reason to skip blobs that are already available locally. Hashing the blob is the only way to indirectly verify the rawdata content stored in the revlog. (The note in that commit about skipping renamed is still correct, but the reason given about needing fulltext isn't.) Differential Revision: https://phab.mercurial-scm.org/D7712