Our interval template started life as `range`, and was supported
wrapping to follow Cassandra's convention of wrapping around the
maximum token.
We later recognized that an interval type should usually be non-wrapping
and split it into wrapping_range and nonwrapping_range, with `range`
aliasing wrapping_range to preserve compatibility.
Even later, we realized the name was already taken by C++ ranges and
so renamed it to `interval`. Given that intervals are usually non-wrapping,
the default `interval` type is non-wrapping.
We can now simplify it further, recognizing that everyone assumes
that an interval is non-wrapping and so doesn't need the
nonwrapping_interval_designation. We just rename nonwrapping_interval
to `interval` and remove the type alias.
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