chore: Remove signed integer warning (#3808)

# Description

## Problem\*

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

## Summary\*

Removes the experimental feature warning for signed integers. Bit
shifting is the only task that remains for signed integers and this
already has a separate error message.

## Additional Context



## Documentation\*

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[Exceptional Case]** 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.

compiler/noirc_frontend/src/parser/parser.rs

@@ -1119,14 +1119,7 @@ fn int_type() -> impl NoirParser<UnresolvedType> {
                 Err(ParserError::expected_label(ParsingRuleLabel::IntegerType, unexpected, span))
             }
         }))
-        .validate(|(_, token), span, emit| {
-            let typ = UnresolvedTypeData::from_int_token(token).with_span(span);
-            if let UnresolvedTypeData::Integer(crate::Signedness::Signed, _) = &typ.typ {
-                let reason = ParserErrorReason::ExperimentalFeature("Signed integer types");
-                emit(ParserError::with_reason(reason, span));
-            }
-            typ
-        })
+        .map_with_span(|(_, token), span| UnresolvedTypeData::from_int_token(token).with_span(span))
 }
 
 fn named_type(type_parser: impl NoirParser<UnresolvedType>) -> impl NoirParser<UnresolvedType> {