Remove use of i32/bool when a builtin type or test-define class type can
work. Make `Sub` user-defines in a test that is testing builtin
functions and not trying to test the prelude, in the same way that it
defines its own Negate. Reduce use of the + operator when it isn't
contributing to the test's coverage, since the + operator needs the full
prelude. Remove use of Core.Print when it's not required for the test.
Move `deduce_nested_facet_value.carbon` to its own file since it uses
TypeAnd, and the rest of deduce.carbon does not, but uses i32. This
means they can each use a different min-prelude.
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Co-authored-by: Jon Ross-Perkins <jperkins@google.com>