The test-case is heavily inspired by:
https://github.com/google/brotli/blob/master/tests/testdata/x.compressed.01
Or in words: A metadata meta-block containing `Y` (which should be
ignored), and then the actual data (a single `Z`). The bug used to skip
one metadata byte too few, and thus read garbage.
Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).
No functional changes.
