Remove instructions necessary for the old regalloc

cranelift/peepmatic/crates/fuzzing/src/interp.rs

@@ -324,15 +324,6 @@ mod tests {
         );
     }
 
-    #[test]
-    fn regression_8() {
-        interp(
-            b"
-            (=> (adjust_sp_down $C) (adjust_sp_down_imm $C))
-            ",
-        );
-    }
-
     #[test]
     fn regression_9() {
         interp(

cranelift/peepmatic/crates/test-operator/src/lib.rs

@@ -6,14 +6,6 @@
 peepmatic_traits::define_operator! {
     /// A `TOperator` type for use inside tests.
     TestOperator {
-        adjust_sp_down => AdjustSpDown {
-            parameters(iNN);
-            result(void);
-        }
-        adjust_sp_down_imm => AdjustSpDownImm {
-            immediates(iNN);
-            result(void);
-        }
         band => Band {
             parameters(iNN, iNN);
             result(iNN);