chore: delete R1CSTransformer (#4649)

# Description

## Problem\*

Resolves <!-- Link to GitHub Issue -->

## Summary\*

The R1CS transformer is currently a no-op as the expression width is
unbounded and we guarantee that expressions will be at most degree 2 by
default.

It also looks increasingly likely that the CSAT transformer code will be
moved into the acir_gen pass so this is redundant.

## Additional Context



## Documentation\*

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[For Experimental Features]** Documentation to be submitted in a
separate PR.

# PR Checklist\*

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

Author: TomAFrench

acvm-repo/acvm/src/compiler/transformers/mod.rs

@@ -6,10 +6,8 @@ use acir::{
 use indexmap::IndexMap;
 
 mod csat;
-mod r1cs;
 
 pub(crate) use csat::CSatTransformer;
-pub(crate) use r1cs::R1CSTransformer;
 
 use super::{transform_assert_messages, AcirTransformationMap};
 
@@ -43,8 +41,7 @@ pub(super) fn transform_internal(
 ) -> (Circuit, Vec<usize>) {
     let mut transformer = match &expression_width {
         ExpressionWidth::Unbounded => {
-            let transformer = R1CSTransformer::new(acir);
-            return (transformer.transform(), acir_opcode_positions);
+            return (acir, acir_opcode_positions);
         }
         ExpressionWidth::Bounded { width } => {
             let mut csat = CSatTransformer::new(*width);