There should be little difference here, because the priority list is
(and was) never serialized with special characters like backslashes or
delimiters that require escaping.

Likewise, no working code actually tried to set such characters.

Still, drop the plain VALUE_STRSPLIT_MODE_STRIPPED and use
VALUE_STRSPLIT_MODE_ESCAPED_TOKENS_WITH_SPACES instead. We should have
a small set of modes that we use for splitting strings.