feat: enable legacy state root tree by default

[yiweichi]

This PR enables reth to use legacy state root tree by default.

Fixes #468

[codspeed-hq]

CodSpeed Performance Report

Merging this PR will not alter performance

_{Comparing feat-enable-legacy-state-root-by-default (fe5289c) with main (c00bd01)}

Summary

✅ 2 untouched benchmarks

[frisitano]

Let's remove rust-toolchain.toml and update the Makefile:

NIGHTLY_TOOLCHAIN := nightly-2026-01-05

.PHONY: fmt
fmt:
	cargo +$(NIGHTLY_TOOLCHAIN) fmt

.PHONY: lint-toml
lint-toml: ensure-dprint
	dprint fmt

ensure-dprint:
	@if ! command -v dprint &> /dev/null; then \
		echo "dprint not found. Please install it by running the command `cargo install --locked dprint` or refer to the following link for more information: https://github.com/dprint/dprint" \
		exit 1; \
    fi

.PHONY: clippy
clippy:
	cargo +$(NIGHTLY_TOOLCHAIN) clippy \
	--workspace \
	--lib \
	--examples \
	--tests \
	--benches \
	--all-features \
	-- -D warnings

.PHONY: clippy-fix
clippy-fix:
	cargo +$(NIGHTLY_TOOLCHAIN) clippy \
	--workspace \
	--lib \
	--examples \
	--tests \
	--benches \
	--all-features \
	--fix \
	-- -D warnings

.PHONY: udeps
udeps:
	cargo +$(NIGHTLY_TOOLCHAIN) udeps --workspace --lib --examples --tests --benches --all-features --locked