Replace the verifyUnusedValue directive with HasNoUseOf constraint

Replace the verifyUnusedValue directive with HasNoUseOf constraint

verifyUnusedValue is a bit strange given that it is specified in a
result pattern but used to generate match statements. Now we are
able to support multi-result ops better, we can retire it and replace
it with a HasNoUseOf constraint. This reduces the number of mechanisms.

PiperOrigin-RevId: 261166863